TestFlight I can't add internal testing group to my recent build

I am having this same issue.

Welcome to the club https://developer.apple.com/forums/thread/721486

I'm having the same issue, after upvoting this post, one of the builds got sent to the test group :). This build was pushed yesterday so maybe there is a a huge delay on distributing to the groups. I pushed two more builds today which haven't been sent to test groups yet. From my understanding, the reason the group is greyed out is because this group is automatically added to the build so you can't do it manually, you have to wait for apple to add the group automatically. If you create a test group without automatic distribution, you should be able to manually add the group.

Same issue for me , i contacted apple support and sent them email with all information that they requested , i just checked the https://developer.apple.com/system-status/ it seams they are working on it

An error occurs when adding groups manually also.

You should fill in the Test Information

Writing a "Test" word in Test Information/Review Notes Filed will solve the problem and the build will appear magically!

The year is 2024 , month is August , and the issue still persists

Today is August 22 2024. Same problem (aside that those web pages are terrible).