The Montage and MODX download pages still only have version 2.0.5, which is not compatible with Big Sur. But the one on Steinberg's site should be fine to use? If so, why aren't Yamaha's download pages updated?

For me, version 3.0.5 released on Steinberg's site works fine. Didn't have yet any issue using the Montage 7.
Regarding update on the Yamaha download page: I found the same behaviour when Steinberg released the version 2.0.5. Took some weeks until they updated the Yamaha download page with it.
Maybe they are still testing before they will release the new version on the Yamaha page.

Alright, thanks, I'll try it.

Is the new steinberg driver working even when not using a montage keyboard? I'm using an DGX 630 and trying to connect to my M1 Macbook. Will there be a new yamaha driver released soon?

The DGX 630 uses the Yamaha USB-MIDI Driver
The Montage uses the Yamaha Steinberg USB Driver

They are different drivers and one cannot replace the other.

Ok thank you Jason. Any update on when the Yamaha USB-MIDI driver will be released?

Not from me. I see the existing drivers work under Big Sur in another forum's thread - but I don't know if that user is using M1 or Intel under Big Sur.

If you're using the latest "-2" version of the driver then I imagine the other user would be using Intel.

I got this response from the Yamaha Support Team in March:

"Hello,

We are currently testing on the M1 silicon processors. Apple did not offer much in the way of prerelease and caught basically everyone a bit off guard with this update.

The last update for the USB MIDI Driver, although a few years ago, has been stable and worked flawlessly up until the release of the M1 processors. We are currently looking at a tentative release date of mid-April for the updated USB MIDI driver."

And in a second follow up in April:

"We are in the process of testing still and it should be released soon."