There might be an issue with the Nuvi and the new "Drive" series. These units expect maps to be in a folder named Map instead of Garmin. I have not tried this for a long time, but I remember when they made the switch, I think I had a Nuvi 1350 at the time. I seem to recall it ignored maps in the Garmin folder. But I also recall the behavior was different on internal memory vs SD card.
This might have changed recently. Will try to give it a test on my Nuvi 3550 and Dezl 760 if I get a chance. If they need to be in the Map folder, you could actually use that to your advantage, and put separate maps in the Garmin and Map folder, and each could have a custom .typ file to make it look best on the different devices.