TV manufacturers do not permit apps to pass high bit rate audio (TrueHD & dts-HD) via HDMI-eARC to external receivers, soundbars, etc. This affects all TVs, not just Samsung.
It is possible for external devices - Blu-ray player, etc - connected to one of the TV HDMI inputs to pass lossless audio via HDMI-eARC.
Movies with TrueHD audio tracks also have a Dolby Digital (AC-3) version of the audio track. If possible, choose the AC-3 audio track, as it will direct play.
If you want to direct play TrueHD audio you will need an Nvidia Shield connected to the TV or to the soundbar. It is the only off the shelf streaming device that will passthrough TrueHD audio.
You can also use Plex for Windows or Plex Media Player on a Windows PC (download). They will passthrough TrueHD audio. However, they do not send HDR video to the TV. They tonemap it and send it as SDR.
