If it works with your UMC or at a supercharger then your HPWC transmitter is bad. If it doesn't work then the receiver side of the car is bad.
It's also possible that there is RF interference at your HPWC location.
I have this issue intermittently on 5.12. Sometimes it works great. Other times I have to open one of the doors as others have suggested and then I am able to transmit the RF signal successfully.
My experience with the charger port door was that it stuck closed due to the rubber gasket inside. After I used some Armor-All on the inside of the charger port, the door no-longer stuck.