…in this case the obvious solution was the right solution. I’ve uninstalled Midiyoke, and that cleared it up. Seems that Midiyoke does not release the drivers somehow? Perhaps i configured Midiyoke wrong, but anyway, thanks for your attention!
In some cases you have to configure MIDI Yoke in the device manager of your Windows environment.
If you have misconfigured that, this may cause problems.
It might also be that Windows assigned different resources to the MIDI Yoke driver after a restart. This is why after installing MIDI Yoke you are advised to do a restart of the Windows system before using the drivers.