"No Builds Available" for new external testers

I get "No Builds Available" when adding new external testers to a build that has already been distributed to 100+ external testers. This happens for all external testers I try to add today:

Existing testers still have access to the build. Creating a new group of external testers doesn't help. The issue happens with both new and existing groups.

The build was previously approved by Apple Beta Review and expires in 36 days. What am I missing?

Follow up: The issue is resolved now with no changes on our side. We are able to add external testers successfully. Maybe it was an intermittent TestFlight issue.

"No Builds Available" for new external testers
 
 
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