When telling Blount to go to an area that is stair-like he can sometimes after reaching the approximate area start walking back and forth between 2 close points. Give him a new destination to end this behavior.
How to re-create it: After Blount comes out of the cabin, set his destination to the point marked by the arrow in the screen shot. (Do not click the actual square but the black area right above it), the bug also occurred for me in Death but there I cannot reproduce it for this bug report.
ScummVM build: 1.2.0 REV 52800 win32
Game version: Goblins 3, CD/DOS/v1.02 (English)
Yes, that's a known glitch in the pathfinding code.
Should be fixed in the SVN repo. Please try a recent checkout or the next daily build.