[lorkadiscovery]

So If I enable IEC, Turn ON AC3 and Transcoding then I get sound on DD but no sound on DD+. The soundbar reports Dolby Digital Plus but no sound comes out.
If I then turn transcoding off and enable EAC3 I get DD+ with Atmos and sound.

So one solution for you would then be: Enable AC3, Enable EAC3, Enable Dolby Transcoding, right? That way EAC3 will work and everything else will be output as AC3 if it is multi channel.

For the Adjust Refreshrate issue. I think the following happens: TV turns off and before the Soundbar is fully up again, output is tried. Under System Settings -> Display is a "Delay Refreshrate-Switch" - set that to 5 seconds and try again, please. 

Ok setting delay at 5 seconds and all the Dolby stuff seems to now play perfectly!

It plays as 3.1 with AC3 and EAC3 set to ON, would it be better to leave it at that or to set it at 2.0 and turn transcoding on?

As for DTS I assume thats just not supported via ARC at all?

Thank you so much for all the help, I really appreciate it!