Sure, geever, but anyway I see the same strange little line scamp mentioned, outlining exactly (!) the impassable area(s). I never noticed those before pathfinding broke.
Maybe the map tiles are not matched correctly when the sys assembles the PATHFINDING-MAP
At least it is an interesting side-effect, that the map reflects problematic zones.
Do you have a hint, if/how we can make further investigations? I'd bet there's something hidden in this context!
Something within the map makes the pathfinding believe, there's an obstacle - an unlinked chain, a height difference? Strange enough, that these areas are quite large and connected to an outline which is "straight-ahead", not curvy. May be at last it's similar to the good ole Pentium thingy (4 : 2 = 1,99999873)?!