First, the shifter stuck has nothing to do with your hydrostat, it is a Transmission Range shifter.
The shifter Arm has gotten out of place in the shift fork. First, you must remove the shifter cover, shift Range Transmission into neutral and reinstall the cover while ensuring the Arm (110) is in the shift forks slot.
This may be a lame suggestion, but I would first try to move the RTV back and forth while trying to move the lever without forcing it. Might require the help of a friend, do not know.
remove the shifter cover from the top of the transmission and put the "pin" back where it's supposed to be. Usually forcing the shifter will force the pin out of the tops of the forks and into where it don't belong, then you're stuck in whatever gear
u can update the shifter pin with new style which "almost" eliminates the pin being forced out. Most dealers know the part number OTOH, I do not have it handy. If you can't get the part number for the kit post back and I'll see if I can find it in my notes
What Henro said! My 2020 RTV-X1140 HST gear shift has been sticky since new and at times difficult to shift from neutral to H or R. Tapping the gas pedal while it is in neutral allowed me to shift into gear while the engine is running. Well, this past weekend it got stuck in L and would not budge. Tried stepping on brake for 5 seconds and stepping on gas pedal didn't help. Did a search and found Henro's suggestion above. Rocking the RTV back and forth (while engine is off and I did not mess with the shift lever while rocking) a few times did the trick! Thank you!