I’m stuck in “Testing as user” mode

I have no idea how I ended up in this mode ” Testing as user” , but now that I’m here, I also can’t get out of it. If I try to “Return to Administrator view” which should exit this mode, It gives me an error:

Your link has expired, refresh the page and try again.

So now I’m really stuck. I’m also having trouble publishing in a separate part of my website as the administrator, so these issues might be related.

I have tried:

server restart

clearing cache

logging out and logging back in

de-activating plugin and re-activating it.