Get your hands on an ATMOS demo disc, or grab a copy of Mad Max Fury Road and have a listen... Make sure the speakers are set up correctly - ie in-ceiling ATMOS speakers need to be represented as being in-ceilings on the AVR's GUI... not upward firing ATMOS units. Check the crossovers / 'size' and levels too. I'm assuming you ran Audyssey?
This industry is not getting cheaper and cheaper, we're simply convincing ourselves that we have to push the cheapest option to customers. #makesonosgreatagain