pMax campaign busted after domain move - anyone else?

jamesaso

managing a PMax campaign for a client that did a full domain migration on 28 April. Since then, it's been a nightmare. spend is _A$1,900, only 2 conversions post-migration, revenue from those was _A$19.7k. ROAS sits at 1,177% against a 260% target. Looks amazing on paper but those two conversions were right after the move - since then, barely any conversions, yet the campaign still burns budget daily.

Smart Bidding clearly still weighting that initial conversion data. Domain migration killed the signal continuity and forced a partial relearning phase. Already planning to tighten the ROAS target, audit all tracking, verify enhanced conversions and GA4 attribution, and review audience signals.

Complication: another agency runs campaigns for a different site in the same Google Ads account and claims our PMax is hurting their performance. My view - PMax shouldn't directly damage a properly structured campaign unless there's overlap in targeting, audiences, auction inventory, conversion actions, attribution setup, or budget competition. But maybe I'm wrong.

Trying to figure out if this is just normal post-migration instability, actual campaign cannibalisation from account structure, or poor cross-domain attribution muddying the data.

anyone dealt with PMax after a domain migration? or managed multiple agencies inside one account? What would you prioritise first? Hoping someone has been through this mess and can share what actually worked.

(For context, someone pointed out that $1,900 is barely anything - yeah, chump change in the grand scheme, but the pattern is still painful.)

conversionninja

Oh, this is so painfully common. It's like watching a beautiful dress get caught in a zipper - the fix is never quick, and sometimes it takes seasons to get the hem back in shape.

Honestly, it's usually even more of a gut punch than that. The real villain? Missing data at the URL level. That's like trying to bake a signature cake without the recipe - you're just guessing and hoping. And that kind of missing thread can unravel everything.

Oh, and that shared account situation? That's a recipe for disaster. PMax is basically a hungry black box that swallows every crumb of data in the account. If your campaigns are sharing a fridge, you can bet it'll eat your lunch.

'Ad ranking' is the magic word that might keep PMax from gobbling up impressions meant for other campaigns. But it's a fragile fence.

But here's the question that really matters: is there a product feed involved? If yes, then honey, you've got bigger problems than a tear in the hem. That's a full-blown rip in the lining.

Hope this gives you a thread to pull on.

davidsearch

Annual $1,900? That's a rounding error on any decent campaign.

funnelhacker

Mate, I've seen this exact pattern bleed ROI dry. Post-migration, PMax basically forgets what a qualified conversion looks like. those first few large conversions after the move? They screw the bidding model hard-skews everything toward volume over quality.

Start with conversion continuity. Verify every event and URL mapping survived the migration. Attribution consistency is the real killer. If anything got doubled or dropped, you're bidding blind. Don't touch bidding strategy until you've confirmed signal integrity

emailwiz

I've been through this exact situation myself - worked with a client last year who switched domains and their PMax campaign went completely off the rails. Took a solid six weeks to stabilise.

the 30-day conversion window is key. Google leans heavily on that recent data, so if you've got zero conversions coming in, your algo has nothing to work with. that's where the death spiral starts.

domain changes always mess with traffic patterns and how the account behaves. Seen that happen with multiple clients - not just the domain swap, but theme updates too. you basically have to rethink campaign structure and prioritise getting those conversions back before anything else.

and yeah, having separate campaigns for two different sites in the same account is a recipe for disaster. It confuses the system and splits your already limited conversion data.

what your PMax campaign is going through? Totally normal. But normal doesn't mean you can ignore it. you need to get conversions flowing again before the algo just gives up.

wordweaver

Oh honey, this is a mess I've seen more times than I've seen bad UGC briefs. That ROAS figure is pure fantasy and you know it. PMax latched onto those two massive sales right after the migration like a desperate seagull spotting a chip, and now it's burning £1,900 a day chasing the ghost of that luck. The model's basically learned the wrong signals because the conversion tracking got trashed when you switched domains.

First thing: pause that campaign yesterday. It won't fix itself-Google's just going to keep overbidding because it thinks every click might be another ten-grand miracle. Go into your conversion settings and either exclude those two freak sales from the bidding algorithm or cap the conversion value. Right now the algorithm is bidding like a tourist in a casino.

As for the other agency blaming you? Laughable. Unless you're targeting the exact same keywords or audiences, PMax isn't tanking their stuff. They're probably seeing general account volatility from the domain change and looking for a scapegoat. Tell them to pull a change history report and show you actual campaign overlap before you take them seriously.

What you really need: fix tracking on the new domain first. Make sure enhanced conversions are firing properly and GA4 isn't lying to you. Set a realistic ROAS target, then let that campaign relearn from scratch on clean data. And honestly? If you can, move that other agency's campaigns to a separate manager account. Sharing one account with two agencies is like two chefs in a tiny kitchen-inevitable chaos.

Two big sales don't make a healthy campaign. Don't let the numbers fool you.

jamesaso

Domain migrations are a nightmare for paid campaigns, especially with PMax. I've dealt with similar feed issues after moving sites. The merchant centre sync itself might be clean on the surface, but I'd double-check the product feed attributes-sometimes the migration tool re-formats URLs or leaves broken tracking parameters that don't trip a warning in Merchant Center but mess with campaign performance.

We had a case where the feed looked fine, Google Ads showed no errors, but the destination URLs had a trailing slash that wasn't there before. Took two weeks of declining conversions to spot it. If your merchant centre support team already cleared it, that's good, but I'd run a full crawl of the feed against the live URLs to be certain. Also check any custom labels or supplementary feeds that might have been overlooked.

marketingmule

That's only about $6 a day - plenty of people spend more on their morning latte. No wonder a domain migration kills performance when you're working with that kind of budget.

jamesaso

22 days, 1st to 22nd May - exactly the kind of lag I'd expect from a domain migration

conversionninja

it's never quite that clean, unfortunately. The feed and the data points are your territory - and Merchant Center only screams about the dramatic, sky-is-falling meltdowns. that silence doesn't mean everything's rosy.

mC support? They'll shrug at you. They can't fix what they can't see, and they don't care enough to try.

what I'd do: crawl through Search Console like it's a neglected attic. that's where trouble whispers before it roars

emmareach

Can you give more detail on the migration itself? Was it a straight domain swap with the same server setup, or did anything else shift behind the scenes - DNS records, subdomain structure, sending infrastructure?

Also, how far ahead did you notify Google Ads and Merchant Center? I've seen a few setups where the new domain inherited no trust signals - no warm-up, no history - and that kills PMax performance because the algorithm suddenly treats it as a fresh, unproven entity. Happens a lot when people only think about the front-end redirects and ignore the deliverability side.