As most on this and the first thread I began having this issue after an update (2016 model) using a Denon AVR-S920w. I've tried all the normal troubleshooting steps; restarting all devices, turning them on in every order, new HDMI cables throughout...
Have a Roku 4640 connected (HDMI) to Denon X3400H - same audio drop problem as reported by many others. Sometimes occurs as soon as the playback starts or occasionally later in the playback (usually within 15 - 20 minutes). Only solution that has worked so far is lowering Roku settings as suggested in the original thread.
"Brettface" wrote: Why would you contact TCL about this? How would they know about an issue that - so far as we know - only affects standalone Roku Ultras, and not Roku TVs? Is your TCL TV dropping audio too?
I have a TCL TV with built in Roku. Roku updated the software without letting TCL know it was coming. I turned on my TV one day in July and the software was updated. Since that date, it has been dropping audio on streaming channels. I had to log a ticket with TCL, the TV maker and they then log it with Roku. They said a lot of TCL TV owners are complaining about this issue.
You might try an update on your Ultra 4640. I just did and went back to Auto under the HDMI/SPDIF settings and I was able to pause and rewind a stream on NetFlix and it appears it plays like its supposed to. The version I got on my device is 4159-29.
I have a 4660 connected to a Denon AVS-S700W & now DD+ is cutting out constantly. I tried a couple different apps & all have the same issue. Everything is connected via 1GbE including Internet so not a bandwidth issue. Changed to DD which works, but now in stereo.
I did more testing to make sure that my Denon wasn't the culprit. i moved an older Chromecast from kids tv to directly into the Denon. Was able to cast Netflix in DD+ without any issues. I sent an email to Roku support but doubt i will get much assistance.