I start the Windows desktop application on two different computers and it doesn't open - the icon opens on the start menu bar, it's apparently actively running, but it doesn't open at all.
The mobile app is working flawlessly. My server appears to be working fine.
Oh thank you so much, that fixed it. It must have been left off screen from when I had a dual screen setup. Weird. Every other app handles second monitor removals fine.
I went to C:\users and then drilled down to \appdata\Roaming@joplin\ and edited window-state-prod.json to an x and y value of 10 each.