I’m not blaming the TV for this one; I’m just explaining how the SoC operates. By default, audio will be sent to both the SPDIF and HDMI out. However; if the display is a DVI display, then we don’t send sound as this would cause problems.
Conversely, last year we had a problem with Vero 2 where one user couldn’t get sound, and only video. For this user, the issue was caused by a long HDMI cable which presented some problems with EDID reading. As it was embedded in the wall; it would have been quite an ask to tell him to change the cable so we had to come up with a work around. Because the EDID couldn’t be read properly; the device fell back to DVI (no audio) modes.
So this means that the SoC can be told not to send audio over HDMI; but usually this is reserved only for DVI monitors which don’t support audio.
It may be possible to leverage this to solve the problem. When I checked the Vero 4K kernel sources however; it doesn’t seem that setting IEEEMode changes audio mode anymore. So it needs further investigation.