MAC Address disappearing on powerdown

I have eight modules (ME-Cs) that lose their mac addresses and reset when they lose power. As long as I reboot via firmware the mac addresses stay, but as soon as I do a power down reset, the mac address resets to the default.

It sounds like it is being stored in RAM instead of Flash, but I haven’t changed anything, so I don’t understand what is different between these new modules and the ones I used last month.

I am using the ESP.

Please help, I have angry customers.