I had issues with Oppo 203, and needing to select Dolby Upmixer (before it detects Atmos), but those issues didn't appear until sometime in the past year. I started to attribute that more to the Oppo firmware than to the MX160 firmware, since all my other devices were okay if plugged in directly to the MX160. For example, I used to connect my AppleTV4k through my Oppo, but at one point I realized that I could get at Atmos from the AppleTV if I plugged it in directly. (I think getting Atmos to pass through the Oppo from HDMI input connected devices used to work maybe a year or more ago). So, I decided to move the Oppo to a different system/room, to directly connecting all of my devices to my MX160, and to replace the Oppo player with a Panasonic UBP-9000 player (I'm much more impressed with the Panasonic than the Oppo at this point for HDR tone mapping and other features/controls). In this case I wouldn't point my finger at the MX160.