Airmap 2000C ???

I just got my new Lowrance Airmap 2000C and am playing with it before I fly
with it. It is different enough from my current GPS (King Airmap IIIC) that
I have a bit of a learning curve to get comfortable with the new unit.

After spending over 30 minutes with Lowrance on hold, then getting
disconnected, I thought I see if any of you have solved this.

I thought I'd load a custom map on the same SD card with the aviation
database, then if I wanted to use it on the road, I wouldn't have to change
cards.

As soon as I power up with the SD card containing the custom map inserted,
no aviation data appears, just road map stuff. This happens despite the unit
being in the aviation mode.

There is plenty of room on the SD card I used for both the custom map and
the aviation database files.

Have any of you run into this issue?

Thanks

Paul
N1431A
KPLU