Maps folder for Cached Maps is not visible

I want to copy some map tiles. There is a supposed to be a Maps folder in the DroidPlanner storage area for this. But the file is not visible there when connected to my Windows PC. If I use the Android App ES File Explorer, I do see a Maps folder where I would expect to see it.

How do I copy files to the folder in Windows if I can’t see the folder?

The Maps folder became visible after restarting my Nexus 7.

Then I could copy maps from Mission Planner to this folder and after getting the right folder nesting structure, the cached maps were usable inside of DroidPlanner 2.