The towbar not locked as noted above.
Or perhaps the Transfer Case is not getting into Neutral.
Maybe practice on a quiet downhill slope. Stop, hold with parking brake while you do the ritual in the Owner's Manual. The release the brake. With your manual transmission shifter in Second and Transfer Case in Neutral, it had better ROLL. If it doesn't roll, the Transmission is holding it because the Transfer Case did NOT get to Neutral. While it's rolling, try to steer. The steering wheel should not be locked since your key is in ACC. Wheel should turn and vehicle should steer while rolling.
I don't know these Zuki/Chev vehicles all that well, but I think some had Locking Hubs. Does yours? If so, does your Owner's Manual say anything about doing something with them getting ready to tow?
