I have a M95S
Is yours manual or switch activated?
Several years ago, the swing shift started doing what you are describing. Mine is electric over hydrolic. The electrical connection in the top of the transmission broke. It is a real pain to change that connection out. The top of the tranny has to come out. The connector is installed from the inside of the cover.
However, I said all this to bring you to a point. If there is not enough hydrolic pressure, then the tranny can not shift from one range to another.
And Kubota has a typo in their service manual. The positioning of the three shift forks are not what they state in the service manual. The high/low range fork which goes to the bottom of the tranny will only allign the shift fork dogs with the gear in low range not neutral. The 1st-4th are in neutral. I had to drop the bottom plate to verify the allignment.
If yours is electric over hydro, check the electric connections first, then the hydrolic pressure.