"Wrong username or password" only on Seafile client on iOS

I have a Seafile server 7.0.5 CE set up and everything works fine for the ~10 devices i have, except for the lone iOS user. When logging in via the app it says “Wrong username or password”. The same credentials work both on another (android) phone and on that phone in safari. None of the other accounts work on the iOS client either.

I reinstalled the app and rebooted the phone multiple times with no change.

Is there some iOS setting i need to enable in Seafile or is there some iOS black magic i need to do to clear some cache that would not be removed by uninstalling the app?