Could be a bug, but also could be me not understanding the rules. France detachment of 3 corps with movement value of 4 moved from Longwy to Luxemburg to Trier to Plalz. Longwy, Luxemburg, and Trier are all forested regions which slow down infantry corps 2 movement points.
Am I correct in my assumption that the corps should have been stopped in Trier? and not been able to continue forward? Does moving through Luxemburg give you a free move?