That's a bummer. I was led to believe that it's "fully polyrhythmic" - from the product page:
"You can set a track with a 4/4 standard signature, and for the other tracks 5/4, 6/8, 15/8... The direct access button enables you to change the left and right numbers without limitation. It's an incredible and easy way to add complexity to your songs."
Now that I reread it, the implication is that one track MUST be in 4/4. I hope I'm wrong on that.
Having to execute all 16 steps is another bummer. The Octatrack will happily cycle back to step 1 after step 13, if I set the pattern length to 13 - for one track, while the other track cycles back according to IT's track length. Granted it was only a brief experiment, but I did try 3 tracks at once, each with a length set to some prime number (no multiples of 4)