User profile won’t work (404).

Hi - we are currently using the plugins ForumWP and Ultimate Member and we have the current issue.

we have the issue that:
When I try to visit mydomain.work/profile/*my-username* I am able to see the content I need but when I try to access mydomain.work/profile/*any-other-user* I get a 404 page not found notification aka "OOops, Looks like we can't find your page".

I tried disabling all of the plugins except the forums plugin and it still persists.
The error log is clean as well.

Maybe there is a problem with the fact that we use Nginx? The issue is recreated locally and on staging as well.

This is a pretty urgent issue so hope getting a reply as soon as possible.
Cheers!