latencymon results look good.
at the top of this thread the poster says dropout protection does not work in studio one with mg3. also there is info on a way to get mpe working further down (kinda looks like a nightmare to me):
if your goal is to record midi, especially for later processing/mixing, then you will probably want a solution which handles mpe without such nonsense.
i certainly understand having wanting to use the software you paid for. but you may be shooting yourself in the foot.
now that you have the general setup with three tracks going consider trying reaper again. it should take less than an hour, if it works that is useful information. if it doesn’t likewise.
also please describe some of your anticipated workflows, how you plan to use the recorded midi tracks.