I have noticed that this is affecting ALL of my korg products. So none of the following show up as IAA instrument, but they work with the workaround
Korg iMS-20
Korg iElectribe
Korg Module
Also affected but maybe by design are
Korg Gadget (This may be necessary because of the MIDI implementation in Gadget i.e you only get midi input on the selected gadget, this means gadget is only really useable within cubasis via sync to clock)
Rebirth. (Maybe because this has only recently had midi input to individual instruments added, previously only able to sync to clock)