Atmos no sound plays with Apple TV with Onkyo Samsung tv setup please help

I ask because you didn’t mention it … Are your HDMI cables HDMI 2.0/18 Gbps/“Premium High Speed” or better? Lower spec cables may support lesser bandwidth, which may not be enough with all settings maxed out, and the way that Apple TV sends the Atmos through (not bitstream like the source, but higher bandwidth to allow some audio manipulation). “Apple TV 4K uses a high bandwidth form of Dolby Atmos.”

I've a similar setup. Onkyo TX-777, LG TV. Apple TV into receiver. TV into receiver. Atmos will work under these conditions: First - Content needs to be Atmos enabled. Try viewing "The Martian" - from the iTunes store on Apple TV. That movie fits all requirements, there may be others but I know that one to work. Second, the TV will not say Amos is working - because the sound is coming from the receiver - not the TV. The receiver will say Atmos enabled, and it will show that on the receiver display. Third, HDMI cable capability - make sure they are 2.1 capable cables.. sounds odd to say. Four, my TV says it is in Dolby Vision during this movie. So, assuming you have the correct amount and setup of your speakers, the receiver will say Atmos when the media has the Atmos content encoded, the TV may not say Atmos, since you're not using the speaker on the TV - you're using the receiver for sound. Make sense?