Somewhere along the lines Steinberg decided to change how you setup external instruments and ever since Cubase 11 came out i’ve always thought the connection between the instrument track and Midi was broken as others have . What i didn’t realise is there is now an extra step (like most things Steinberg seems to alter ) to assign Midi to the External instrument track and that is , once you have creatived your midi device setup you need to close it and revisit it to setup your desired midi ports as explained very well on this fantastically informative channel .
Now all my instrument tracks are working perfectly ,as they should .
(2) Cubase Skills: External Instruments - YouTube
One other thing , if like me you do a lot of mixing and run on high buffers and suffer with latency while playing , hit the delay compensation button in the left button corner of the project page and this will bring your midi latency down so low you can play in time .
hope you find this little bit of info useful
Hoo hoo hoo and a Happy new year