The symptoms have all the signs that the Control Pilot connection from the charge point isn't working for some reason, either it's not enabled or there's a fault somewhere.
What's supposed to happen is that the charge point (the box on the wall) sits with the Control Pilot signalling wire in the lead and car connector at +12V, via a 1kΩ series resistor, what's called State A in the standard. When plugged in to the car, the resistance between the Control Pilot pin within the car charger connector and the earth (the PE pin on the connector) loads down this +12V to +9V. The charge point senses that the charger has loaded this pin down, and starts transmitting a 1 kHz pulse train to the car, that swings between +12V and -12V at the source in the charge point (before the 1kΩ series resistor).
This pulse train has a duty cycle (the ratio between the time it spends at +12V and the time it spends at -12V) that signals to the charger the maximum current that is available from the charge point supply. The charger then adjusts its internal setting to not draw more current than this, and when ready it loads the positive going part of the Control Pilot signal to +6V. The charge point senses that the charger has done this, and turns on the contactor to supply power to the charger.
In this case the charger is detecting that there is a plug in the connector on the car, but is not detecting the Control Pilot signal from the charge point. As the charger is working normally with the Tesla UMC, it would seem that there is no fault either with the charger or the car connector. Everything points to the charge point, or perhaps the charge point cable or connector, being at fault, as it doesn't seem to be sending a valid Control Pilot signal to the charger.