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.