ADM Authoring for Dolby Atmos - test enviroment

I’m trying to perform some tests with ADM Authoring for DA and I find a behaviour that I do not understand
this is the TEST ENVIROMENT:

  1. I created a test project using Cubase 13 Pro on a Mac Book Pro with MacOS BigSur 11.7.10
  2. The test is executed in my Studio where I have a 7.1.2 configuration driven by a MOTU Ultralite MK3 interface that drives the 10 outs
  3. In the test project created 10 MIDI tracks connected to 10 Halion MIDI channels. Every Halion channel is routed independently to a BED group that I configured as 7.1.2
  4. I created a DA Out channel 7.1.2 and routed BED group to this DA channel. This way I can ear every channel correctly in the Studio. Every channel is routed to a single loudspeaker by using VST multipanner utilities (in short: every channel produces a mono-like signal routed to a single loudspeaker)
  5. Using this configuration I produced an Audio Mixdown export in 7.1.2 format. A .WAV file of 250 MB has been created by Cubase 13
  6. I listened to this .WAV file from my Iphone 14 enabled for Dolby Atmos through AIrPod Pro hearphones and everything seems to be ok. I think I can hear the spatial sound and HRTF functions from IPhone works correctly on this material (the sound mix changes when I turn my head)
  7. I performed the same test by connecting the Iphone to Samsung Q930B 5.1 soundbar and the result seems to be ‘more or less’ ok. At least I can ear every channel
  8. Then I repeated the test after ADM Authoring configuration. A new Standard Bed channel (7.1.2) has been created and an output channel 7.1.4 with DA Render plugin too in the same project
  9. Then I routed my BED group channel to STANDARD BED group channel
  10. When I play the project and I open DA Render plugin I see correctly the first 10 objects corresponding to bed and their volume. In this test i did NOT use objects, only bed
  11. So I used the command ADM Authoring for DA to produce the BWF File
  12. Cubase 13 produced a .WAV file having a lower dimension (187 MB)
  13. The PROBLEM is that when I listen to this file, through Iphone speakers, AirPod Pro or the sound bar I can hear only the 2 FRONT CHANNELS (objects 1 and 2). all the other objetcts of the bed are very very ‘far’, you cannot hear them

is there any error in my set up?

thank you for helping