It's likely the same diode discussed here:
viewtopic.php?f=30&t=24560&hilit=diode
Watch the YouTube video, which explains how to diagnose it.
If that's the same diode, people have been fixing the problem by installing an external diode into their EVSE.
Having said that, I wonder if you could instead install the diode into this device:
https://emotorwerks.com/products/chargi ... /juiceplug
That way, you could take it with you so you can still use public L2 EVSEs