Not able to add a group of test users in iTunes for an app which is review

Question

I submitted an iOS app which was in review process and had one default test group "App Store Connect Users". A day after that I tried to add another test group to this build, and it got successfully added. Build is submitted to review again when a new test group is added.

Now, I am trying to add third group of testers to this build. When I click the add icon next to groups, a pop shows with the message, "You can only submit one build from version 1.9.5 to Beta App Review."

I am wondering how it allowed to add the second group, but now allowing to add the third group of users. Ideally, Once the build goes through the beta test review, all the external groups that I would have added, should receive the invitation to test.

Answer 1

As per Apple doc says

External Testers and Groups Once you’re ready, you can invite up to 10,000 external testers who do not need to be part of your team to beta test an app that you intend for public release on the App Store. You can organize external testers into custom groups and share different builds with each group, depending on which features you want them to test. Before external testing can begin, the app must pass Beta App Review to make sure it complies with the full App Store Review Guidelines. Only the first build for the beta version requires a full review.

You can add anyone to this group, and they can test builds using the TestFlight app. Builds may need approval from Beta App Review.