Hmmm. I tried the setup several times but still no go.
Problem is, my AVR also received a FW update. So the bug might be in that FW actually.
Strangely, the 'add device wizard' does run a test during setup which is able to turn AVR on/off correctly. But normal operation, no go.
I guess I will have to use my raspi to log all CEC traffic and see if the TV doesnt send a on/off command or the AVR ignores it. so boring.