Can't play Dolby TrueHD + Atmos

[Drake97]

Hello,

First I want to advise that I searched the forum but I didn't find direct information or maybe I didn't search well.
My drawback is that when I try to play content with TrueHD + Dolby Atmos audio, on my soundbar it appears as Stereo PCM.
When I use any other audio format (DD, DD+, DAtmos, DTS, etc) it shows it without problems, it is only with TrueHD + Dolby Atmos the "problem".
My setup is a 65" LG C4, a Samsung Q600b Soundbar and a Chromecast GTV 4K.
I don't know if it's because the content is in 7.1 and my bar is only 3.1.2 but it shouldn't come out as stereo, maybe it should come out something else.
Do you know why this detail ? If you need more info I can give it.

As a fact, when I bring my ear close to the bar, I can hear the different channels (voices in the center and sounds on the sides), but I still have some doubts.

PS: I attach a video link where I press the info button on the Soundbar and show which audio track is set (TrueHD).

Video test

SBar Specs