I’m currently facing an issue where I can add Friends but they are not displayed in the “My Friends” repeating group. However, I can see they are added and removed when I add/remove them (button remove).
Common problem when working with User datatype. Privacy rules by default prevents the users to be listed, searched etc. You have to add some proper privacy rules to the User datatype: Protecting data with privacy rules - Bubble Docs
This is how you should design w.r.t. your app design. But when you check all of them, you should see that it is working. But this technically means opening all data of the users. So be careful in this front, and put some thought on it.