We’d be happy to take a closer look at things for you. Could you please provide a bit more information around your audio setup, your multichannel devices, and how they’re all connected?
I think that might be a change in Roon. I don’t see it either. If you choose Downmix as needed, Roon will detect 5 or 7 channels and will downmix 7.1 to 5.1 if your setup is 5.1. If you choose Channel mapping only, you will lose the Atmos sounds if playing on a 5.1 system.