Hey All...got a MX+ recently and had issues connecting to my 2018 SHO non-pp using their OBDLink App. Here is the OBD protocol to select if u have issues while trying to use the OBDLink app.
Settings > Communications > OBD-II Protocol > ISO 15765-4 (11 bit ID, 500 Kbaud).
This may be obvious to some but being a rookie..not so obvious to me and it took two weeks for their Developers to figure it out. A picture of the OBD port sent to them was the clue that cracked the case.
Thx to ZSHO and particularly to SHOdded for his advice and direction via PM. You guys are the best!