Been through this exact cycle more times than I can count, and the fresh-account workaround always feels like progress until the same ads flatline again. 🙃
Before migrating anything healthy, capture delivery status at campaign, ad set AND ad level the moment spend dies. Then audit the boring stuff: billing, account spending limits, bid/cost caps, schedules, page restrictions, domain, pixel, catalog, account quality. "No flags" at the campaign view means nothing when an asset-level limitation is quietly doing the damage.
Here's the trap nobody talks about: the new-account test can hide the real dependency, because you're swapping billing history, trust, auction context and asset combos all at once. a colleague ran this exact test last quarter and chased the wrong fix for weeks.
if the ads do deliver in the fresh account, send Meta support the old/new account IDs plus exact timestamps and delivery screenshots. That escalation actually gets responses. "It randomly stopped" gets you a copy-paste reply.