So just as a temporary workaround, create a virtual switch "humidifier VS". Use that VS in a rule, that if door closed, allow humidifier VS to turn on humidifier outlet. If door open, do not allow outlet to turn on.
Here is my initial thought about how I think I would handle this. I added a delay so humidifier wouldn't go off/on/off/on every time a door is opened. That logic may need a tweak, but at least it would only go on once here and not flip-flop.
Edit: in case it wasn't clear use the humidity VS in the bath fan app...