Cannot join friend/friends & worlds not showing up

My friends list never shows up but when I go to add friends, it says we are already friends. Because of this, when I want to join my friend in their world, it gives me an error message. I've been able to "fix" this issue once by deleting the app and re-downloading. Now when I try this trick and sign back into my Microsoft account, my worlds are gone and it still shows that I have zero friends.