Same problem with an NUC7i3BNK here, too, regarding the bitstreaming of HD audio formats. Installed Windows 10 last Thursday to confirm it's somewhat related to the DP to HDMI conversion chip's firmware. Initially no HD-bitstreaming worked in Kodi under Windows, applied the 1.66 Megachips firmware update which fixed it there. As stated by the OP in this thread this doesn't help with LibreELEC though. Guess we'll have to wait for an updated driver for Linux or something along those lines.