First thoughts would be that the pushrod length is wrong.
If this is the rod and slave that came with the engine then probably not wrong, but if you have used a slave or rod from your original motor then there's the chance of a mix up possibly?
I think the rod for your S2R motor should be 335mm.
The earlier 900 rods are 325mm
Aftermarket slaves such as Oberon come deep enough to take the 335 rod and supply a 10mm spacer so you can use the 325 rod.
If you are using the longer rod with the spacer, you will get the solid feel you report as it will be topping out the pressure plate and locking.
If there's an Oberon on there, try tapping it on something solid to see if a spacer comes out, and check the rod length too.
Could also possibly be the rod not going fully into the top hat in the pressure plate bearing for some reason, maybe the O-ring displaced in it or just full of something solid?
You could also have a pinned rod. The pin has to locate in anti-rotation slots in the slave. Later Ducati slaves have the slots and Oberon do too. If you don't have the slots the pin will have nowhere to live and will jam.
Some info here..
http://www.ukmonster.co.uk/monster/s...t=oberon+slave
Final thought would be that your slave is knackered.. Not a polite thing to mention I suppose, but a possibility.
Edit… Forgot to mention that the pin can simply be knocked out if there are no anti-rotation slots for it.