I ran into the same problem the second map I tried. The pin was by two landmarks on the map, the CC screen, it's map, uoam, the EC screen, and it's map. Went through in a search pattern twice, checking three spaces away, all 4 cardinal directions, every three steps, with GM mining. In a grid extending past the landmarks. All I succedded in doing was irritating my hands, wrists, and arms from all the mousing and clicking.
The chest I went after first I found by a landmark in 30 seconds. The only things I carried away from it ( a L1) was the gold, regeants, gems, and one bracelet with three things on it with very low numbers.
I sold my 220 maps in the evening. Thunting is now a masochistic experience for anyone with arthritis.