I have loaded 3 of the Garmin 24K TOPO map sets and all of the remaining states (not covered on the Garmin maps) TOPO maps from GPSFIleDepot onto a 32GB SD card. The problem is my 64s is not recognizing all of the maps at once, it's either the Garmin maps or the GPSFileDepot maps, but not all. If I load the Garmin maps first on the card, they will show plus a couple of the GPSFileDepot maps. When I load the GPSFileDepot maps first to the card they will show and none of the Garmin maps will show. Seems to be a limit as to how many maps the unit will recognize, is this what is happening? All maps were loaded to the unit through BaseCamp.