2013 Volt - Intermittent charge issues

So here's a weird issue that I can't figure out. Periodically I will take a short drive in the morning (maybe 10km or so), then come home and plug in. Yellow light will stay on and I will get the message "Unable to charge" and my range is now down to 0. Turn the car on and get the "Service High Voltage System" and "Propulsion power reduced" messages. OK. Remove 12v negative, put it back, messages are gone, car will charge fine and range is back to where it should be, no issues.

I just replaced the 12v battery with a new one thinking that was the problem, but it still persists. This has happened to me twice in the past month, always in the morning. I'm wondering if it could be my L2 charger (using an EVSEUpgrade.com Nissan unit) or maybe the dreaded coolant sensor issue?

Dealer had "fixed" this in the winter by "reprogramming" the battery computer but I'm assuming they just reflashed it and it reset the errors.

The only codes I could get were from a check engine light that I normally receive when there are power quality issues with charging (P1E00 & P0D22). After I reset the 12v there are no codes and everything works fine.

Specs:2013 Volt, 106,000km, L2 charging (EVSEUpgrade.com Nissan unit @ 20amp) plugged into 30a dryer plug

Help!