I can confirm that the Day Blanking setting is not "sticking" across a reset here either. It repeatably goes back to the default of Never blank.I never noticed this before but that's probably because I haven't been using that setting for anything lately.
At a glance it looks like there is no code to retrieve that setting from SPIFFS. I'm looking at an up to date pull, around lines 2400 - 2525.
Look into it later when the dust is clearing off the crater.