Third-party tools and driver uninstallers like those designed for KORG products can mess up the registry. The midifixreg tool currently fixes only the location used by 64 bit apps, not the one used by 32 bit apps.
There are many 32 bit apps out there, but these are known to be impacted
- MIDI-OX
- ROLI Dashboard
- Novation Components
- Much older apps like the EDIROL PCR editor
- Korg KARMA and related apps
32 bit registry location:
Computer\HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\Windows NT\CurrentVersion\Drivers32
64 bit registry location:
Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Drivers32
For 32 bit apps to see MIDI ports, the following entries must exist in the 32 bit location
midi REG_SZ wdmaud.drv
midi1 REG_SZ wdmaud2.drv
These can be manually created by right-clicking in the registry location and choosing new->String Value and then modifying the value afterwards (it's a 2-step process: create an empty value, then modify the value to provide the required wdmaud*.drv
The midifixreg tool needs to be updated to also fix this registry location.