Try adding this patch to config.plist/KernelAndKextPatches/KextsToPatch:
Comment: HDMI-audio, port 0105(12), 0x0a260005 0x0a260006, 0x0d220003, 0x0a2e000a, 0x0a26000a
Find: <01050900 00040000 87000000>
Replace: <01051200 00040000 87000000>
Name: com.apple.driver.AppleIntelFramebufferAzul
AND/OR this one:
Comment: HDMI-audio, port 0204(12), 0x0a260005 0x0a260006
Find: <02040900 00040000 87000000>
Replace: <02041200 00040000 87000000>
Name: com.apple.driver.AppleIntelFramebufferAzul
Hi again - OK, I tried both of the patches above, on their own and together but unfortunately there's still no Displayport output and switching the display on or off or connecting / reconnecting the cable causes a crash.
I did lose my sound with those patches in place though, so something changed and maybe we're close? Restoring my original config.plist has got things back to the way they were (with sound).
I'm happy to test anything you suggest and if you need any more info just let me know.
Heading in to work soon so may not be able to get back to this until the weekend.
Thanks again for taking the time to look at this for me. Hoping the answer is out there somewhere.