on my Marantz pre-amp and receiver, they both have an option listed as sound mode and that allows me to take an ATMOS signal and play only the Dolby TrueHD layer or a DTS:X signal and play only the DTS-HD-MA layer or combo of anything to include Dolby Surround or DTS: Neural X
perhaps you need to toggle through these options while using the player with an ATMOS/DTS:X source and it should pop up as a selection.
also, most modern receivers allow you to set what you want on a "per input" basis so if that's an option, each hdmi input can be told to play a particular audio effect. perhaps your receiver offers such a feature.
found this out because I had changed the audio option for something and forgot, went to play ATMOS and it wouldn't play, had to go back and reset it to what it needed to be to give me ATMOS.
hope this helps.
TCL-65R615, 55P605 DV/HDR10 & 49S405 HDR10, Philips BDP7501, BPD7502 UHD Players
Oppo BDP-105D, 105, 93, Marantz AV7702MKII, NR1607. Xbox One S
Emotiva XSP-1, XPA5,UPA2, UPA200 & Mini X Amps, ATV4K 32gb
Speakers, Polk SDA-2, Monitor 10A & 5A, Axiom M80,
VP180, QS8, M2, QS4, ATMOS 7.1.4 & 5.1.2 NYGiants!