Audio downmix issue with v17?

I’m having a similar issue with my OSMC on an RPi 3. I believe it first started with 2017.03-1. Today I upgraded to 2017.04-2 and the problem persists.

RPi 3 connects via HDMI to a Yamaha RX-V767 receiver. TV is a Sony with 24 Hz support.

Passthrough is off. Output is HDMI only. Channel setting is 5.1.

With setting “Player -> Videos -> Adjust display refresh rate” set to “on start/stop”, for a 24 fps video the refresh rate is updated and my TV shows “1080/24p”. (GUI refresh rate is ~60 Hz.) The audio source is 5.1 channels but with the resolution/refresh rate update, the receiver is only registering a 2-channel input (2.1). If I manually toggle “stereo downmix”, the audio output is updated to the proper 5.1 channels.

Changing the setting “Player -> Videos -> Adjust display refresh rate” to “off”, preventing refresh rate change, and Kodi properly sends the 5.1 channel audio to the receiver from the beginning.

Those are my two workarounds for now.

I can’t see anything in the logs which would indicate why this is happening. If this is not a know issue, are there verbose logging options for this refresh rate update or something else?