Can no longer enable Atmos in Windows 10?

[Domingo]

Weird issue. Starting on Saturday morning, I could seemingly no longer enable Dolby Atmos in Windows 10. Normally it's my default since lots of Netflix content uses it. I'm using it via the Nvidia HDMI-out.

Yet now no matter what I do, it won't take. Swapping my speaker array to it doesn't save. Trying to enable it via spacial sound gives me an error. I've tried unplugging things, swapping AVR inputs, uninstalling sound drivers, and just about everything else under the sun.

The only thing I can do to bring it back is to swap my HDMI driver from Nvidia's to Microsoft's. Yet that seems to only work temporarily. After a reboot, the Nvidia one swaps back over.

Weird caveat - playing movie files and disks that have embedded Atmos soundtracks actually works 100% fine. It's just the Win10 implementation.

Did Dolby release an update that broke something or anyone else ever encounter this? It doesn't mean much for anything but Netflix. With Netflix it's night and day better than the normal DD+ stuff, though.

 

[Domingo]

...and I think I've at least found a partial fix. Uninstalling only the Virtual Audio Driver followed by a clean install of the full suite of Nvidia drivers seems to allow me to swap back over to Atmos. At least temporarily. When rebooting I seemingly have to swap back to Atmos every time (or I get a "device not found" error), but at least it kinda works. I wish I knew what caused this and how to fix it on a more permanent basis. It's genuinely tough to fully purge audio drivers. Even when I do, it's like my PC remembers things about them...including the custom name I gave them and their previous settings.

 

[Domingo]

After researching this a little more, it seems like this relates to something Nvidia did with more recent releases of their HDMI audio driver. They CAN still work fine, but they're way more finicky with certain AVR handshakes.
I've noticed that I not have 2 new/different audio inputs/outputs that weren't always there.