Loudness track in nuendo doesn't match results from the dolby atmos renderer?

I’m finishing my album in dolby atmos using Nuendo 12. Now I’m working mastering the tracks and getting the loudness specs correctly for distribution.
I’m running into some issue regarding the measuring of the loudness. I’m using loudness tracks and analyzing the loudness to make sure I’m on the correct numbers. Problem is after I export the ADM file and open it on the Dolby Atmos production Suite the loudness analysis is differing a lot from the Nuendo measuring .
Foe example:
If I measure in Nuendo an integrated - 18.7 LUFT the exact same track will measure in DAPS at -5.7 LUFT. Also same apply for the true peak:
Nuendo measures -8.10db and DAPS will measure +3.0 db
Also even more confusing is that the difference is not consistent .

Any idea what’s going on here? Is the Nuendo loudness very inaccurate? maybe I’m doing something wrong? Is there other ways to measure integrated loudness ? any body else can check this?
I really need some help here…is driving me crazy!
Thanks !
BTW nuendo atmos renderer gives me a very close number to the loudness track and besides can’t run an average analysis since is only in real time.

Sure everything is set up correct in the Setup Assistent?
(ADM export window)


I think so…there arent too many settings…but it looks fine…all green dots