Same issue, I can only add builds to the internal test group, when I try to add a build to the external test group, this message appears:
"Some of the information required to submit your build for external testing is missing"
I have reviewed the test information and it's complete, also tried to add comments in different languages for testing, and test information but same behavior.
Topic:
App Store Distribution & Marketing
SubTopic:
App Store Connect
Tags: