Grid shows instead of an offline map, help!

If you selected the downloaded offline map to be active and then on returning to the main map you see just the grid with labels and no map, like this:

Then it means that for the area or zoom currently shown on the map there are no tiles to show in the downloaded map. Either you have the map at the zoom level that is not inside the downloaded map data or area doesn't match. Grid shown in such case gives you information on the current zoom level at which data are missing (Z(oom)=14 in the case above is missing). If you are sure that you downloaded the area that is being shown, then please just zoom in/out to get inside the zooms that were downloaded.

The advice would be to always download the map from zoom level 2 to the required higher level. Lower zoom tiles take very little space, but allow to find the downloaded area easily on the map by zooming out.

You can also use the following trick to find the downloaded area on the main map. Activate the "map browse/edit" mode by tapping on a "follow me or not" triangle button:

Label with the map name will turn into button to enable you to focus on the downloaded map region:

Tap on this button and main map will move/zoom to fit in the downloaded map.