No DTS-HD but Dolby TrueHD is fine?


Using a Minix U9 with 8.95.6 installed and it’s been awesome (moving over from libreelec) but with one weird issue. When I try to play a video with DTS-HD I get no sound at all. TrueHD is fine (and my amp tells me it’s TrueHD etc)

So if I then go into settings whilst the video is playing and turn passthrough off and then back on sometimes it starts playing the track correctly whilst sometimes it stays silent. Also if I have both DTS-HD 7.1 and 5.1 tracks switching to the 5.1 works and then switching back to the 7.1 now also works???

Videos can be either 4k or 1080.
TV is 1080p max.
Amp can and does work with all HD streams.
Setup is u9 --> amp --> TV

All and any help greatly appreciated as I’m going mad!