I do it like this => cast it 2x quickly with right click and go at once with "m" into the map. The map is uncovered then and remains uncovered.
If you cast it - a high pitched sound comes - does this happen to you? Maybe the room on your map shows another dungeon? All dungeons in the map are in the same level.
Example => if I am in a cellar and scroll on the map, I can see rooms belonging to another dungeon nearby - even if I can't reach it.
