Nginx Proxy Manager - can't login after server restart

So, I think I ironed out a lot of things to get my selfhosted setup running, but it seems that Nginx Proxy Manager is causing me troubles. When I restart my server, the container with NPM restarts as expected but I can't log into the web ui (the website comes up, but when I try to log in nothing happens) and it also doesn't provide the expected proxy functionalities. I'm not sure what happens - any advice would be welcome. right now my only workaround is to delete the container and make it from scratch, but this also means making all proxy hosts + certificates from scratch as well ...