Since the hack on lemmy.world and a few others, the admins have killed sessions that were logged in. If you are experiencing any weirdness, try logging out of the app and then back in. Fixed the issues I was having this morning. Shout-out to Jerboa development channel on Matrix for the fix.
I was also having issues with the Jerboa app where I kept logging in, but the app said I wasn't logged in when I tried to access my profile or subscribe to communities.
I ended up needing to clear both cache and storage, then log back in. I'm on Android.
Thank you for this comment, I was logging out and back in over and over getting more and more frustrated, I just cleared the storage and the cache and bingo! Working like a dream. It didn't help that I was having trouble opening some of my documents on a work system at the same time, I was starting to get paranoid that the computer overlords were deleting me.