Ok, so I think I found a bug
On Mountain Labyrinth, when I kill of the Stronghold for main quest first (100 Frost Ibex, Ravaging Ox, Ghastly Wolf), the boulders for killing of the eastern stronghold are no longer clickable. So can't use dynamite anymore to get to the camps and stronghold there.
This applies for the bottom and the top boulder, and the patches of snow that you can normally clear with the shovel.