LOL! ATmos capable phone? Didn't know there was such a thing. I hvae an iphone, but it's 5 years old. Also, another side comment. I put those albums that Jonathan mentioned into my library. When I played the Blue Oyster Cult, it didn't play in atmos, my AVR switched over to 5.1, but it only played out of my left front speaker. LMAO! Must be some setting, not sure about all that.
do you know which model iPhone it is? afaik iPhone 11 (Pro/Pro Max), 12 (Mini/Pro/Pro Max), the XR, XS and 2nd gen SE all handle Atmos.
the BÖC is an old Quad in Dolby Audio not Atmos and an older Vn of the Apple TV firmware had such a channel assignment bug, you need to update your Apple TV's firmware