[Krypton] Passthrough not working

I recently upgraded from Kodi 16.1 to 17 Beta 2 and noticed the passthrough audio setting was not working.

OS: Windows 10 (anniversary update)
CPU: Intel i7 4790 3.6 GHz
GPU: Intel HDGraphics 4600
Audio Device: WASAPI HDMI-PR-SC5509
Passthrough device: same

HDMI connected to Onkyo PR-SC5509 AVR receiver

Source: bluray disc DTS-HD 7.1

On the controller it shows: Multich PCM 7.1 (so the input is PCM and not DTS)
On the PC while the movie is playing (O key): DCA 32 bit 48000 bits (appears to be decoding the DTS audio track)

I had upgraded from JRiver to Kodi a year or so ago and so I tried it, the passthrough worked perfectly.

I then uninstalled Kodi 17 and reinstalled Kodi 16.1 and enabled passthrough.

For the same source I now get:

Onkyo: DTS HD Master 48kHz 7.1 (which means it is now getting a DTS bitstream from the PC)

So both JRiver and Kodi 16.1 passthrough work perfectly, so the problem is not windows or the drivers, but is definitely something in Krypton. I am using the same system, video and audio settings in both versions so I don’t think it is that. I have reverted back to Kodi 16.1 and hoping that someday Krypton passthrough will work on this system. I am willing to assist in locating the problem if needed but for now thought I would simply report it to the development team. Didn’t have any problems with Krypton, looking forward to returning to it.