From "The Guardian" live feed: "JSpOC, located at Vandenberg air force base in California, also says there are 44 pieces of debris in the vicinity of the cargo

From "The Guardian" live feed: "JSpOC, located at Vandenberg air force base in California, also says there are 44 pieces of debris in the vicinity of the cargo vehicle and part of the rocket body." I'm speculating then that it got nailed by something. With the large drop in propellant as you noted, maybe something nailed a pressurized tank? That could punch a hole in it, and maybe the resulting thrust from the tank is what drove it's spin.