Issue in TestFlight - 1 tester has an invalid name or email address and wasn’t added

Getting error in AppStoreConnect when adding tester in test flight tab

1 tester has an invalid name or email address and wasn’t added

Why does this error happen? is a bug in the test flight? kindly help

There's already a thread for this issue https://developer.apple.com/forums/thread/702988. Bug was reported over 6 months ago and there's no resolution yet.

Issue in TestFlight - 1 tester has an invalid name or email address and wasn’t added
 
 
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