Having this same problem…Has been working fine for two years but just downloaded Windows 10 latest huge update and saying no driver.
The H9 just uses the standard built in Windows driver for USB Audio devices. We heard from some people who had their Bluetooth connections stop working after installing the Windows 10 Creator update, but this is the first we've heard of the H9 no longer being recognized as a MIDI device. The Windows 10 Creator update apparently greatly improved the trouble shooting help in Windows 10, and the people with the Bluetooth problems were able to use that to sort their problems out. Could you try checking there for tips about this problem?