CAA Nepal have issued a circular that requires all helicopters landing at altitude to have bear paw skid pads attached amongst some other directives It may indicate that the skids sank into snow which resulted in the helicopter rolling over.
I did some mountain training in the Drakensberg in South Africa and landed on the Devil's Backbone which was at about 10 000 ft in a Squirrel and the controls were as mushy as hell and all control inputs were really sluggish. From what I can see the altitude of the Lobuche Helipad is quite a bit higher.