Transmission gets stuck in gear

While there could be other things this is almost surely a failing clutch.

What happens is when you press the clutch, and the pressure plate does not fully disengage the clutch then it is hard to shift, and you will lose power because the clutch is slipping.

Here are a couple of guides that will help with this:

https://www.2carpros.com/articles/clutch-doesnt-work-sometimes-or-not-at-all

https://www.2carpros.com/articles/clutch-symptoms

While we don't have a manual on this vehicle, we do have a couple guides that will help with replacing this:

https://www.2carpros.com/articles/throw-out-bearing-replacement

https://www.2carpros.com/articles/how-to-replace-a-clutch

If it were me, I would inspect and replace the clutch as this is the likely issue with this. Thanks