Don't know if dam is non random, but I just got the same error message (with somewhat different numbers):
ERROR: LET_PathMove: Actor movement is out of sync: 137:132:1 should be 135:135:1 (step 3 of 3)
The error occurred while trying to move a sniper up the tower. On one round, the sniper made it just to the top of the first flight of stairs. As the game would not let me move the guy further into the second flight, I decided to try and crouch him in case there were some actor height issues. It seemed to work at first, since the grid turned green at the top floor, but the sniper did not move and the grid turned blue again. At this point I decided to try and move him just to the stairs and not beyond when I found a spot there which gave me a green grid. As I clicked to make the guy move, he started his crouched motion towards the stairs, then out the builduing through a wall, and back to the main menu (I started the map in skirmish mode). Checked thre console and the error message was there.
I also recall seeing the same error yesterday with an alien who was coming over the dam towards the tower walked over the railing and into the water just before the game crashed back to the main menu.
I hope this description helps reproduce the issue.
Still, progress has been made with pathfinding. About a week ago I could not move soldiers into the tower building.
Cheers!