2020-03-24 12:04 PM
A reset caused by BOR causes all but six words of EEPROM to erase to 0x00000000. A software reset with "NVIC_SystemReset();" is OK. EEPROM contents are retained, as expected.
2020-03-26 03:20 PM
I found the problem. There was a subtle timing issue with the "losing power" firmware and the startup firmware following a reset. (The product has a super-cap to allow the microcomputer to generate audio and visual "loss of AC power" alarms.)