Thank you for pointing that out.
I tried it again and it still doesn't show the data, although the data is only stale for about 30 minutes and now many hours passed since I updated it manually.
Thats how it currently looks like:
And this is what I get in the console:
Note that the most errors come from the official facebook plugin. I still don't know why because facebook login works just fine.
Signing in to Realm works too. One line above the blue marked area it says signed in and it also shows the Realm user id. And when a new user signes into facebook a new user account will be created in the Mongodb database through Realm.