Had this happen 3 times now and all of them were on race day during Ultra runs.
I have a PacePro plan planned and navigation for the course activated. Everything works fine until I skip through the screens and enter the map screen.
The watch instantly reboots. After that at least the activity is still there and I can resume it. Course is still being navigated but PacePro (and ClimbPro) are gone.
Watch is on v13.22