bk6111cng

Today, garmin release firmware 5.60 to fix this problem. Changes made from version 5.50 to 5.60: Fixed potential issue with GPS+GLONASS

My 64s which was bought at 2016 started doing the same thing yesterday, remove battery and reset to factory defaults didn't help. I started to check the files in Garmin directory, after remove the GPS/MT.NVM file, the problem had fixed.