Hi there,
If you could provide a bit more information I would be happy to help you.
1. What version of ArcGIS Enterprise are you using?
2. Can you consistently reproduce the issue?
3. When did this start happening?
Thanks,
Jessica
Hello @SamehMahmoud77
Including the answer to the queries by @JessicaLM. It would also be helpful if you share the following (If possible):
Additionally, have tried clearing the browser cache and trying to "Add member" after that.
Hope it helps!
-Archit
Greetings @SamehMahmoud77
In addition to the suggestion from @ArchitSrivastava of clearing the browser cache, I would suggest:
Let us know if any of the above helps.