This works.
I am not a midi wizard, but I believe you have to specify OT’s midi input channel and separately the OT midi output channels (to the A4).
The midi input channel can be changed in the midi menu. I think you have to chance auto ch. from off to the channel of your midi keyboard, which is normally midi ch. 1.
Then in the midi track you set your midi channels the same as the midi channels in the A4.
Good luck.