I have this problem of DTS-HD 7.1 only detected as 5.1 channels both on DTS and Dolby. I have a capable receiver Onkyo 828.I recall that when I used intel based Openelec intel hardware, it worked.Can you check if VIM can do the 7.1 pass-through?
OK, thanks for you feedback, will confirm first then reply you here.
We are also working at LiebreELEC-7.1 and LibreELEC-8.0, will release new ROM then. PS: Current ROM is based on LE-7.0.2, and LE-8.0 is still not stable yet.
Issue solved with LE 8. Passthrough of dts-ma 7.1 works perfectly