CEC not working at boot on Panasonic Viera

[te36]

Panasonic TX-L42ETW5W, ca 2012. RPI 3B connected to first HDMI port, XBian current (04/15/2018).
RPI is powered by 2x USB output from TV, so it powers on whenever TV powers on.

Upon power on, Kodi reports CEC, but it does not work. When i then change input on TV to some other HDMI port and back, CEC does work.

This is without anything else connected to other HDMI ports. If i connect another CEC capable device to port 2, results are even more confusing, some keys don't work (menu for example), others do.

*sigh*

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Oh, forgot to ask:

In an older kodi installation, the CEC config allowed to configure the HDMI port that the RPI is connected to. Now this option has vanished from the config menu. There is still the "physical address (overrides HDMI port)" config option though. WHich of course is confusing, because of the "overrides HDMI port", which is referring to the vanished part.

Is the option to configure the HDMI port for CEC some place else, or if now, why was it removed ?

*strange*