Another thing to consider is that both BIAB & RB have MIDI driver settings. Maybe the Korg is not set as the default driver for MIDI.
The Korg isn't a driver. The computer and it's sound card use one of several drivers.....ASIO, MME, WDM, or WASPI (I think it's called) The driver in the computer handles the audio and midi in/out. External devices only need drivers in some cases to let them function fully with the computer and will sometimes load that to the computer automatically, but that driver is a different driver which serves a different purpose.
This really doesn't matter because the Korg will appear only as a midi source for midi inputs. Either directly as a KORG midi source or as the interface midi input on the interface being used. As long as the computer recognizes it as a device on it's USB port if it's a USB device, it will be available to anything that can use the midi coming from it..... or in my case, I connect my midi source to my interface and when I have a midi track, I select the Focusrite Midi source from the drop down. No driver from the device is required in this setup. ASIO for the sound card "discovers" the inputs available..... both audio and midi and lets you choose from them.