I had the same problem! i've changed a few clutches now in on the Evo's but this time no gears. After 3 times the box coming out and me looking at it and speaking to a few specialists they said it was strange after checking all the basic stuff and not finding the fault. So anyway i decided to fit a new paddle clutch and it made no difference till the clutch fork arm snapped and looking at It, It had stress points and must have been flexing hence why i couldn't engage gears.
Any way all fixed now and driving. That was one random fault that i have never seen.
Hope you get it fixed.