Bravia Sync says device connected to HDMI1 - it's on HDMI4 and always was

[RickDasterdly]

TV: Bravia A95L...

I have a Ugoos AM6B+ player connected to HDMI4. It's always been on HDMI4. I've been trying to get CEC working from the Sony remote when using the Ugoos player, for pause/volume etc. It doesn't seem to pass anything through to the box whatsoever. 

Perhaps that is because, when I go to the TV's Bravia Sync settings, it tells me that the Ugoos is connected to HDMI1. Previously the TV would switch to HDMI1 every time I activated the Ugoos box, until I disabled the CEC on the Ugoos that tells the TV to select its input. Nothing is connected to HDMI1 and I want to use HDMI4 because the box can do 120Hz. Sony in their wisdom only put HDMI2.0 on the first two ports.

Clearly the Sony is messing this up... anyone know how to fix this or have any similar experience?

[RickDasterdly]

To add...

I've just found a previous post reporting the same issue: https://community.sony.co.uk/t5/android-tv/bravia-sync-seems-confused/td-p/3948463

The advice in that thread to cold-plug the devices does not work here. I've tried every possible combination with everything disconnected from the mains, clearing the enabled devices list on the Sony between every step, unplugging power again, reconnecting the HDMI (and only that one device plugged in), powering up the TV first, or the Ugoos first, or both together...

In every case when I re-enable BraviaSync, the box gets listed as being on HDMI1 and CEC does not work.

The Sony's software is getting this wrong.