Spent a full week chasing a phantom bug. Numbers in our Amazon DSP went down. Bids looked fine. Tags looked fine. Servers looked fine. The bug? The cookie pop-up. Here's what happened, and how to fix it without breaking anything else. The thing nobody told us Amazon changed how it reads cookies in 2026. There's a new signal called ACS — the Amazon Consent Signal. Every cookie tool has to send ACS in a very specific shape. Old tools don't. Even tools that say they support TCF v2. ACS is its own thing. If your tool doesn't send ACS, Amazon turns down its tracking. Your DSP audiences shrink. Your sponsored ad numbers drop. None of it throws an error. That's the worst part. How to fix it in four steps Step one: check if your cookie tool is on Amazon's approved list. Most aren't. Step two: hook the user's choice into the dataLayer the moment they click: window . dataLayer .…