Yes, I’ve followed those pretty much (my amp is 5.1 so number of channels is set accordingly).
I found another earlier thread from someone who was having a similar issue:
His amp is also a Pioneer and similar model to mine, so I wonder if there’s something Pioneer amps don’t like about the way Coreelec bistreams DD+ ? But, as I said, the amp is fine if I use Libreelec to stream DD+