New issue on my home PC today! Occasionally, when the computer is locked and the screen has entered power save mode, budgie-panel appears to forget which desktop it lives on. There's no coredump, so it's not crashing. Journalctl output shows messages like this:
May 12 15:59:55 summit budgie-panel[1604]: manager.vala:420: No monitors detected. Skipping panel repositioning.
I can fix it by opening Budgie Desktop Settings and moving the panel to a different position; then everything works fine until the next time I leave my system locked for a while.