When the car acts in unexpected ways, I find it helpful to RTFM
You can set your car to 'Charge immediately' from the phone app, if getting into the car's menu is too hard.
It does sound like you have it set to a different mode, like 'Departure Time'.
I have had situations where I had to cycle power to my home L2 EVSE. It somehow loses it's brains/logic. Maybe a dip in the grid voltage does it.
Once it gave me a check engine light, which Onstar gave me the code and title of, "HV charging system...."
I had the exact same code with my Volt and knew that it goes away on its own after 2 or 3 charge cycles.
Used '14 2LT w/ DCFC.
+61k miles. Only one LONG visit to the shop....
GM needs Modern Troubleshooting tools for Modern EV's.