Lots of reports about Map flakiness in the last year or so. Two steps that sometimes have helped others with these symptoms:
1. Go to Library, exit LR, restart LR, go to Map. Does it work now? Exiting LR directly from the Map module can produce these symptoms, more often on Windows but sometimes Mac.
2. Try resetting LR's preferences:
LR sometimes soils its preferences file, and resetting it can fix all sorts of wonky behavior. That article explains how to restore the old preferences if resetting doesn't help.