Bid cap
Running a catalog prospecting campaign (COD, Algeria market) on Meta, ABO, optimizing for conversions. Bid cap was set at $4, ran clean for 4-5 days averaging ~$3 CPA — but only spending ~20% of daily budget.
Since underspend was consistent, I bumped the bid cap to $4.5 to unlock more volume. Day 1 after the change: great, ~$2 CPA. Days 2-3 after: spent ~50% of budget each day with zero sales.
My working theory: raising the cap didn't change targeting, just widened how many auctions I'm competitive in. Since pixel volume is so thin, Meta's per-user value model has wide error bars and the bid edit likely reset learning phase, so it's now spending the extra headroom while re-exploring with a noisier model instead of exploiting the pocket of good users it had already found at $4. The one good day right after the change might've just been residual momentum from the old learning state before the reset fully hit.
Questions for anyone who's dealt with small/local auctions like this:
- Does a $4→$4.5 bid cap edit (12.5% increase) actually trigger a learning phase reset, or is that only tied to budget changes?
- Is there a better way to unlock spend on a supply-constrained low-volume auction without blowing up learning phase?
- Anyone run bid cap successfully in a market this thin on purchase volume, and if so what protected you from these dead spend days?
Not looking to switch back to cost cap — already confirmed bid cap outperforms it by 3x on my account. Just trying to figure out if this is normal bid-cap volatility in a small auction or if I broke something.