Probably nothing wrong with your MODX, probably nothing wrong with Cubase. The problem is clearly a Windows issue.

I hesitate to do any ‘adjustments’ to your Windows Registry via a forum like this — You are best served by either phone support or direct support from someone who can help you overcome your computer issues.

After you see the message that the Driver cannot be loaded, you can stop, right there. Doing anything else just adds to your frustration.
It’s like the car has no engine, the fact that one of the tires is low on air, or the lock on the trunk is broken is of no concern, the car isn’t going anywhere until you get that Driver opened. Worry about the tire and trunk later.

Reading your post, first thing I would suggest is to make sure you are connected DIRECTLY to the computer. That means NO HUB.
You don’t mention whether you are or are not using one; and I’ve seen customers do everything (including reinstalling Windows, unnecessarily) — all they needed to do was remove the HUB (they didn’t think it important to mention that they were using one... Don’t.

Continue getting help locally. Problem with the computer are best handled via phone support or direct support.

Let us know if you get the Driver recognized. Good news the driver is installed, as you can see the Driver’s Control Panel.

Calling support (for Windows or the Computer Brand) will lead to the inevitable joy of them saying "Contact the Driver Manufacturer.... not our problem"

Calling support (for Windows or the Computer Brand) will lead to the inevitable joy of them saying "Contact the Driver Manufacturer.... not our problem"

I think the original poster was in contact with the right people. But thanks for the encouraging words.

This registry key?

HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindows NTCurrentVersionDrivers32

Because I have 20 entries there and everything is working.

I just do not think this business about more than 10 is true if the above is the registry key you're referring to.

I think your support team is mixing up things here. There was an API limit of 10 MIDI ports. This is not related to how many drivers you have installed in driver32. Newer APIs have a much higher limitation - still no relationship to the amount of entries in the "Drivers32" registry folder referenced above.

This limitation is primarily a problem with older MIDI software. Software that uses newer calls - as Cubase 10 or 11 should most certainly use - would not have this kind of limitation.

That said - your MIDI drivers that are connected to USB devices have a way of littering your system with zombie entries. If you plug in your instrument to different ports - then a new instance of the driver will be "installed". The Yamaha Steinberg USB Driver used by MODX and Montage will present issues with WebMIDI when there are these zombies out there. It's best to clean house every so often.

Cleaning house can be done by uninstalling the Yamaha Steinberg USB Driver, then rebooting without the driver installed, then installing fresh. This will clean up all of the old entries.

If you haven't done this already - I would do this before mucking around with the registry. If you think Cubase is fouling up the works - just wait until you tangle up your OS with bad edits and try to undo those. Best of luck if that's the plan. Backing up keys is OK - but some doors are one-way if the system "reacts" to registry keys being set a certain way. The best way to back up your system is to ghost your drive bit-by-bit. Shy of that - creating a restore point may be OK. I wouldn't "trust" this and would still suggest "ghosting" your drive (as in Norton Utilities Ghost - but there are others out there and I'm not sure if Norton is the leader in this anymore). Doing this would allow for you to do anything you want and restore back.