Using Basecamp 4.3.4 on Mac OSX 10.9.4 with new GPSMAP 64s device and 64GB microSDXC (reformatted as FAT32), I have 5 maps installed on the SDXC: two Topo 24K, two City Navigator, and one BlueChart g2 (US All & Candian West Coast).
Every time I start BaseCamp, it re-reads the BlueChart g2 map, showing the blue slider moving from left to right over the label "Reading map ...". When the slider completes its progress to 100% the slider disappears but the label "Reading map ..." remains (forever as far as I can tell).
If I click on the label (or icon to the left) "Reading map ..." a dialog appears saying "BaseCamp could not switch to this map" and "The selected map cannot be displayed until it is completely read from the device."
I can proceed to use other functions in BaseCamp, but the Reading map ... label never gets replaced with the map name. The other four maps on my SDXC card appear to complete normally, showing their titles, and can be selected.
Subsequent to this never ending read, if I attempt to quit BaseCamp, the "BaseCamp" menu item in the top level Menu Bar becomes highlighted (in blue) and remains that way until I force quit the application using Option+Command+ESC.
The next time I run BaseCamp, it goes through this same process all over again.
