Microsoft has recently updated the Windows operating system to introduce a new version of MIDI.

As part of this update, virtual MIDI ports have been affected and may no longer function as expected. Microsoft has subsequently released the following information outlining a workaround for users experiencing these issues.

https://microsoft.github.io/MIDI/kb/how-to-change-api-mode/ 

Please note: 

Editing the Registry on your computer is done at your own risk.