I now also have that behavior. Installed the update yesterday, and last night got the "can't determine" message. I checked VT on my computer and it did not show a plugged in cable graphic. Refreshing the didn't help, nor did a re-start of VT.
Went out to the car, and checked and indeed cable was plgged on. Unlocked car with fob thus waking it up, and center console confirmed the car believed it was plugged in. Once I did all that, I came back in and VT correctly displayed the cable plugged-in graphic.
This leads me to believe there are some sleep algorithm changes. Oddly, both scheduled start and scheduled HVAC events in VT seem to work without issue. Just the cable-check.
My next step will be to disable sleep altogether and see what happens.