Jeep Cherokee Shifting Problem

I have a 1996 Jeep Cherokee with a 5 speed manual transmission and about 120,000 miles. It generally runs great, but recently, I am having a frequent problem where, from a stop, it is sometimes impossible to shift. It feels like you are pushing the shifter against a solid wall. So far, I have always eventually got the thing into gear.

The problem gets worse after several miles of driving. And it only happens from a dead stop - shifts fine when moving. The car has a new clutch, transmission and clutch fluids are fine and I just replaced the clutch master cylinder. Any thoughts?

I wonder if they used the proper transmission fluid? Was there some kind of problem before the transmission fluid change? What was it changed?

Most likely the transmission shaft is being turned by the engine. It could be the pilot shaft bearing, dry input shaft splines, a step on the input shaft splines, axial runout of the clutch disk, something wrong with the pressure plate, or something causing incomplete release of the clutch. For trouble shooting purposes, you might chock the front wheels; jack up the rear wheels; and put the car on stands. Then run the engine in gear; release the clutch; and see how much brake pressure is needed to stop the rear wheels. That will be one way to ascertain if the clutch is dragging and how much.

By the way, does this transmission grind into reverse when this happens or is the reverse engagement also blocked by a syncro ring.