It's best practice rather than strictly 'mandatory' to hard reset/[Only registered and activated users can see links. ] both before and after doing any software/firmware updates to avoid such behavior. It's certainly the first go-to "immediate action" if you experience anything weird with a Garmin or any other similar electronic device. In Garmin devices sometimes just a byte or so of corruption in it's non-volatile memory can cause what you experienced requiring a reset however sometimes just a restart which rewrites the GarminDevice.xml is sufficient.