Chuck --
Yes -- we had precisely the same problem -- and it happened shortly after a servicing of the Honda engines (by a Honda mechanic) who had failed to properly connect the shifting lever after the servicing.
We were facing upriver tied to a dock (on a fast moving river), with dock on port side and rocky shore a few tens of feet on starboard -- tight spot. We had a couple with an infant baby aboard. With both engines running, left the dock with port engine ahead, starboard in reverse (to spin the boat in the tight spot) -- and the starboard engine failed to shift due to the same problem you had. Boat barely turned without hitting the rocky shore (by reversing the port engine after it was right angles to dock and shore). Now too close to shore, in fast moving current to get back to dock -- below us, a large barge was tied to shore. Finally clear of rocks, gunned the port engine(and only engine functioning) and (now under the high prow of the parked barge, with current thundering under the barge bow) barely cleared the bow and got into the river. It was a near tragedy (especially for the baby) if we had been plastered against the bow of the barge, and Halcyon had rolled under the barge due to fast current.
Finally back to a nearby boat ramp, still shaking from the incident, Joe's suggested fix took care of the problem.
I called the dealer, not angry, but to tell him the problem so he could doublecheck those nuts to assure it never happened to someone else. THAT part WAS unsatisfactory. He defended his "overworked" service man and essentially said "tough luck" and don't bother him with such trivia. Needless to say, we have had no further connection with that dealer.
What did we learn? Don't trust engines to properly function in a tight spot (that was my fault), don't trust a mechanic to properly service an engine, and don't think that all Honda dealers are concerned about the quality of their service (even when a safety issue is at stake).