Right. Otari wants you to strap pin 2 to pin 1 in your cable so you don’t have this unterminated antenna (essentially) in your cable. Remember they are directing you to do this based on a pin 3 hot system. If it was a pin 2 hot system the you’d be strapping pins 1 & 3. Now look again at the detailed information on monoprice regarding your cable you bought. Yes, that’s right, they e already done it for you, pins 1 & 3 are connected. So there’s nothing to do there if you convert the Otari to pin 2 hot.
Now here’s where I get confused again. So you did try the phase reversal adapter and it didn’t work, huh? First of all, get comfortable with this: reversing pins 2 & 3 is reversing the phase. That’s what you are doing, if it is a balanced circuit. Yours is not, at least as far as we know. So by reversing pins 2 & 3 you are just moving your signal conductor from pin 3 to pin 2 where you need it. So if the adapter reverses pins 2 & 3, that should work. Why I doesn’t I don’t know. I wanted to verify that what it does is reverse pins 2 & 3 but there was nothing Sweetwater confirming that. Maybe you should set your meter to ohms again and verify what pins connect to what pins from one end to the next. It should be this
pin 1 to pin 1
pin 2 to pin 3
pin 3 to pin 2
So check that out, and you also may want to try my suggestion with the hookup wire. Not eloquent but would rule out a bigger problem with the system.