Another failure mode to consider when talking about side-loading on belts is belt impingement on the frame itself. On many of our tank tread robots in years past, the belt could come partially out of alignment, sticking out past the bottom of the frame during a T-bone, but afterwords could self-correct; however if the frame had a sharp edge on the bottom when pushing occurred and the driver attempts to drive, the result can start enough of a cut in the tread that it compromises the entire belt and cause it to fail in a similar method to the previously posted pictures.
In addition to proper tensioning, I recommend checking the bottoms of the drive plates for sharp edges and clean up what you can.
