Why is Meta spending 100% of my budget on ONE ad and ignoring the rest? (Sales Campaign)

For context, I run marketing for a live music venue, so these are short-window concert campaigns where creative testing matters fast.

What’s confusing me is I have OTHER active campaigns right now that are distributing spend across creatives normally and performing much better ROAS-wise.

But these 3 campaigns specifically:

• 1 campaign
• 1 ad set
• 6–10 creatives
• Purchase optimization
• ~$800 lifetime budget

Meta instantly picks ONE ad and completely ignores the others:

• $360 spent on one ad, all others $0
• $450 spent on one ad, all others $0
• $198 spent on one ad, all others $0

Not “low spend.” Literal $0.00. No testing at all.

What makes this feel even weirder:
I turned OFF the only ad getting spend in one of the campaigns to force delivery to the other creatives… and the campaign basically stopped delivering entirely for ~15 hours instead of shifting spend to the remaining ads.

That’s the part making me wonder if this is some kind of delivery bug/glitch.

Has anyone else seen this recently? My ROAS is way worse when Meta behaves like this compared to campaigns where it actually tests creatives properly.