Noticed my mode changed to morning at 12:00 last night, normally set to 615am. Applied the 2.3.1.138 patch late last evening. Switch to night mode went okay prior to the update.
How is the mode change at 615am triggered? If you click on the "info" box in the log for the 12am mode change it should change app 261 and may tell you what made the change. Otherwise it may be a case of looking through your different rules and apps to understand where it occurred.
I'd also wonder whether there could be any relationship to this thread.... unlikely, but if @gopher.ny is looking into that part of the platform may be worth mentioning....