I have a laptop with a USB keyboard and external HDMI monitor:
Laptop on left (secondary display) ------------------- Monitor on right (primary display)
When I launch Joplin, it appears on the laptop's panel. That's OK, but when the monitor isn't attached the panel becomes the primary display, obviously, Joplin then starts offscreen to the left and I have to Alt+spacebar followed by M to select "Move" from the window menu so I can drag / arrow it back to where it's visible.
I've moved it around before shutting Joplin down, etc., but nothing has worked yet. Not the end of the world by any means -- I can work around it. But it's curious. Anyone else seen this?