I’ve never been hot on a customer being in the machine room, however it can be a set of eyes to record information in your absence. Leave off the controller covers and suggest to the customer when this issue occurs, use their smart phone to photograph or write down what’s being displayed on the LCD screen and if possible video the CPU white box to capture all outputs there. Anything other than “NORMAL” on the LCD screen and normal scrolling red LED’s might be a clue. Or similarly set the address to monitor door inputs and do the same thing. I vote as well for rechecking the parameters for valid floors and parking. Also verify floor information (addresses and ID) for both cars.
🤪 I see this was last week, so maybe you got it figured out.