I'm not the OP, but I'm having a similar problem. (Sorry to hijack the thread, but hopefully the same advice will help both of us.)
I've run the Memory Map software on my PC, then right-clicked the route on the map (following
KB 75) and saved it to the UserData folder on the Adventurer's SD card. (In my case, that's my J drive.) I then disconnected the Adventurer in Windows, turned it off, and unplugged the USB cable.
When I turned the Adventurer back on, I went into Maps, then clicked the Settings button (a hammer and spanner), and chose "Overlay | List..." from the drop-down menu. That showed a new dialog box, so I chose "Routes" from the drop-down list. However, the list below was empty, i.e. it can't see the route that I saved.
It's only a short route (16 waypoints, 3km), so it shouldn't be too taxing for the device. Am I making an obvious mistake here?
Edit: I've figured it out! I needed to click Overlay | Open... rather than Overlay | List...
It's working fine now, so hopefully this helps someone else.