I don't want to sound paranoid Sharkbait but I think you are on the right track .... I suspect the crew of your Sd.kfz. 251/1 AUSF. C, has been turned by the Soviets.Their orders now are to crash the mission the moment they see your Tiger on a winning streak.
With your experience in mind, I am going to do a last minute change to my crews tonight before I play the game and see if my delusional theory is right....