Prefetch maps

I am prefetching maps of my property because Tower only uses Google maps and they are over 5years old but Bing maps are at least after the trees where cleared in a heavily forested property.

When I choose the area it fetches to and beyond 22 but in the directory it wont show lower than 19. Now this is ok but in Tower it by default is obviously lower so I end up zooming to a white screen which is pretty annoying.

Can someone offer a solution or tell me where the files are going because MP seems to be downloading to somewhere.