Sorry for the late reply...
I have had this happen on at least 2 occasions.
I cut the power and then plug it back in (reboot) and it grabs the GPS as soon as it loads up the maps.
There is a 'reset gps' buried somewhere within the menus, but I can pull the plug and reinsert it faster than I can find the reset!
I was curious if anyone tried this ‘reboot’???