[avoidconflictz]

@avoidconflictz see if you can work out when this issue started - is it present in LibreELEC 8.2.5 (Kodi 17.6), or is it only an issue in these LE9/Kodi 18 test builds, and if so can you identify the first of these test builds with the issue? It could be a kernel issue, or a Kodi issue.

Can you provide links to sample Dolby EAC3+ and DTS HD files that might allow someone else to reproduce the issue?

 I can provide sample files with EAC3 but so far every file with EAC3 causes the same problem. Even those short sample clips I got from public resources. An HD audio must me played for at least 30 seconds or longer and then EAC3 stops working.
I tried 8.2.5 in Feb 2018 and audio passthrough didn´t work at all for any audio type on my NUC6CAYH. Probably due to old intel drivers in the kernel and incompatible HDMI FW in my NUC. There was no change when I upgraded the HDMI FW and BIOS to the latest so I focused on LE9. The funny thing is that I´ve been using LE9 for about 3 months now and found out about this only three days ago because I haven't played any video with EAC3 until now.
Let me try few older LE9 test builds to see if any previous works better that current. It might take an hour or two.