I've played that mission 3 times and had absolutely no problems with path finding regarding the berm. There are other path finding issues that I have encountered (moving through gaps in walls seems a lottery at times). However, the more I play the more my commands seem to alleviate them. For instance I now leave more space between vehicles and plot turns with more waypoints than I started with. I'm sure that future patches and increased awareness of the best way to plot commands will improve things but it's not unplayable as it is.