Volkemon,
I don’t know specifically if windshield breakage occurred on class C RVs when trying to level with only one jack but I do recall reading apparently it happened from time to time on Class A in the early days of leveling jacks. That I think that was probably the motivating driver in the fully automatic leveling system. As I recall I think Phoenix elected to go with the bidirectional system that required two jacks at a time deploying. Not sure why PC elected not to use the fully automated system. Perhaps it was cost but I don’t know that for certain. There may have been an option for the full auto system.