try what i mentioned in the recent posts.
it is not perfect but it work(ish).
for me right now hdmi works only in one condition: tv is turned on and plugged in, reboot pc, login, and the audio should be on the tv (even if muted, sometimes, just unmute it).
whatever you do (turn off, sleep, reboot), it won't work again until you do the above.
btw: this is not annoying at all for a product over 1000€...way to go sony OR intel...