Help! My main variation’s ads suddenly stopped getting impressions — SBV went to zero, SP is dropping. Other variations are fine.

I had a similar issue in Canada last year. Support said “system can’t retrieve ad delivery” — same exact wording. It took about 2 weeks, then suddenly started working again. No changes on my end. They said many sellers were affected.
You’re probably just stuck waiting for Amazon to fix it on their side. Keep the cases open and keep asking for updates, but don’t spend too much time rebuilding campaigns — if it’s a system issue, your old campaigns will come back when they fix it.

Here’s something I learned from a case where ads suddenly stopped:
It turned out the product had been flagged as “adult” by a competitor in a different marketplace (Canada). The flag carried over to the US marketplace, blocking all ads. The seller support agent in the US couldn’t see it because it was a cross-marketplace issue.
To check: open a case with the global team or ask them to check if the ASIN has any restrictions in other marketplaces. If you find something, you’ll need to fix it in that marketplace.

Quick check: did you recently update or merge variations? Sometimes when you update a parent-child relationship, the system resets something on the child ASIN. I’ve seen cases where a simple merge caused the main variation to lose indexing on all its core keywords.
If you did any variation changes around the time this started, that might be the trigger.

I had almost the exact same thing happen last year. One variation, out of nowhere, lost all ad impressions. Other variations fine. Cases went nowhere.
After about 10 days, it came back on its own. Support eventually admitted it was a “system glitch” on their end. They said they were seeing it across multiple sellers.
If you’ve ruled out everything else — payment, Buy Box, adult flag, product type — it might just be Amazon’s system being weird. Keep opening cases, keep asking for escalation, but also know that sometimes it’s not on your end.

The fact that your SBV campaigns went to zero while SP still has some impressions is interesting. I’ve seen this before.
A few things to try:
First, rebuild.

• Pause the old campaigns
• Create new SBV campaigns with the same creative, but use dynamic bidding (“up and down”) and set bids at the suggested range
• Give it 2–3 days

Second, check the video asset.

• Is there anything in the video that might have triggered a review? Words, visuals, claims?
• Sometimes Amazon silently disapproves a video without notifying you

Third, use SD campaigns to test.

• Run a Sponsored Display campaign with VCPM bidding on this ASIN
• If it runs normally, the ASIN itself isn’t blocked — it’s something with SP/SBV specifically