I am slowly migrating my game development stack to a fresh installation of Arch Linux, however I ran into a interesting issue where Unity Hub would forget projects that I had added manually into the project list. The log files also indicated something in the filesystem was fucked up, so I set out to investigate.
Turns out that if you run Unity Hub as root (via sudo), caches and configuration directories get assigned to the super user and is generally no bueno. Do not run Unity Hub as root.
Add a project to your hub project list, then close the Hub and re-open it. If you find the project is missing from the list, then you’re likely facing the same thing I had.
To fix this, simply delete “unityhub” folder inside the following directories, replacing “YourUsername” with your account username. Do not delete any other folder as they’ll contain settings to unrelated things.
Then relaunch the Unity Hub as a normal user and then reconfigure the Hub settings. Quit the Hub, the changes should stick now and your project listings should no longer disappear into the void.
Hope this helps!