Multiple maps in Garmin 810
 

I have multiple OSM maps loaded in my unit. Does that confuse the unit somehow? I've recently had problems with loaded courses. Everything works fine for maybe 20 miles and then the map screen suddenly locks up. The cue sheet screen continues to work fine. I've had my software updated but that did not help.

I have multiple maps on my 810 and not had any issues that I can attribute to having them loaded. It does boot up much slower than just having the basemap.

I don't have a Garmin but OsmAnd is buggy on my iPhone. I've downloaded the maps I need so they're accessible offline but it usually takes two or three tries to access, with the app failing a few times, and it's painfully slow. I'm using Google maps offline more often now.

I have 2 map sets on my 810 and have navigated multiple times on courses out to 40 miles, no issues.

You don't want to enable multiple detail maps that overlap.

If the map is disabled, it's ignored.