Let's start with the root cause here, and then when solved, there may be other problems. Problem #1 here is lack of slave movement, not the clutch itself (could be a problem also)
12-13 mm at the slave is not enough, that has to be sorted first. The effort reduction kit (which I would throw away immediately but which works for some) doesn't help, because it of course presses less fluid for the same amount of pedal stroke. So even if all works perfectly, the room for error on adjusting the clutch is less.
The obvious thing is that if you have the right master and slave and no bubbles and all adjusted right, you have more than 12-13 mm movement at slave. Do you have an OEM master, or something cheap or fancy? I recommend a master from Roland in Germany, he has the orig size ones built in Italy, a little more expensive, works perfectly.
"Is your MC the original ~19mm BORE? with the slave bore of ~25mm? vendors do sell a long stroke slave which has a smaller bore. (smaller bore gives MORE stroke from the same MC)". But please, don't keep your effort reduction kit and invest in a long throw slave, because then you defeated the purpose of the effort reduction kit. You can't cheat physics, less effort at the pedal means less movement of the slave. Pure physics.
Here's what I would do. I would spend some money on this. Why? Because not having proper clutch disengagement can quickly ruin your ZF synchros, and then we're talking $$$. I would buy new OEM master and slave [Apologies Peter, re-reading the entire thread, I see now that you have a good master and slave from Roland], (OEM, no effort reduction kit and no long throw slave), bleed until I got proper slave travel. Only when that is succesful would I move to check the clutch. If at that point you can't adjust the clutch properly (see how in my 4 step instruction posted earlier in this thread), then you may need a new clutch. But fix the slave throw issue first.
(After searching a bit on this forum I found that a standard slave should have 5/8"=16mm and a long throw should have 3/4"=19mm. This will of course vary, but it confirms that your 12-13 mm is not as it should be)