I am not sure if this is the reason. One time I parked on a soft gravel spot. Even though I used my levelers with plastic blocks under them, one side sunk. It actually bent the plastic block. The outcome was that my door would not close. I actually tied it shut that night. In the morning, I discovered the bent plastic. The frame had torqued. This would put tremendous pressure on the door lock. That may be the cause of the lock breaking.
Since I changed to heavy duty
Utility Blocks, I haven't had the issue.