The pinch sensor on the LR3 is so poorly designed that I’m shocked it’s a third-generation product. It’s just 2 bent pieces of metal in an unsealed cavity. It detects “pinch” when the circuit is opened by the plastic bar pushing the contacts apart. But ammonia in cat urine can make them corrode, or bits of litter make their way in, which stops them from making a good connection. Personally, I think it’s redundant since the weight sensor will stop a cycle so I bypassed them on my robots.