No Ground Fault when coming out of sleep

Hello all,

I have very happily had a OpenEVSE charger for a few years now, it was professionally installed and has been working well.

I have it setup so that it sleeps when our electricity tarrif is expensive and charges when it’s cheap. This means that under normal operation it sleeps for a long time and then starts charging for a few hours over night.

When doing this it seems to reliably error with a “no ground” fault, however if I plug the car in and immediately start charging it works with no problems.

I haven’t changed anything about the setup or done any updates before this error started occurring, so I am at a bit of a loss.

I was hoping to get some advice on if this is likely to be a charger or firmware issue vs a wiring issue for which I should get an electrician round.