No valid corner found for path find

[Nemo84]

I'm currently doing the 6th battle in the 1st Inf Div 42 short campaign with a modified German OOB and I keep getting a "No valid corner found for path find" message in the game log when the Soviet turn is calculating. Now I suspect this is due to the map being divided in 2 by a huge river with only a single chokepoint bridge to cross, and the AI can't find a decent path to cross for all of its infantry swarms. Some units are trying to cross, but at the current slow rate they'll never get a foothold on the other riverbank. I added a savegame as attachment.

There is a second thing I've noticed. Now I don't know if this is related to a potential problem with pathfinding AI as above or just WAD, but I did notice in the previous battles that the Soviet infantry is advancing somewhat piecemeal. Armour tends to rush ahead and can easily be isolated, but by the end of the battle the AI still has a couple dozen infantry units in or near its deployment zone. This only seems to happen when the AI has a huge infantry force with little armor.