I visited my local Honda dealer and asked him about this problem. He told me there were two things that commonly caused this.
The one he saw most often involved the black hand grips can slip upwards coming into contact with the paddles and the resulting friction doesn't allow the paddles to retun to the neutral position.
The next was that grass clippings would actually collect in the cavity under the deck where the transmission sits to the point that the transmission could not pivot freely enough to return to neutral.
You can also watch this video which covers the troubleshooting and correction of the problem.
https://youtu.be/tw3OuXRVtkA
The one he saw most often involved the black hand grips can slip upwards coming into contact with the paddles and the resulting friction doesn't allow the paddles to retun to the neutral position.
The next was that grass clippings would actually collect in the cavity under the deck where the transmission sits to the point that the transmission could not pivot freely enough to return to neutral.
You can also watch this video which covers the troubleshooting and correction of the problem.
https://youtu.be/tw3OuXRVtkA