My uneducated guess is that your clutch slave down at the back of the clutch actually isnt disengaging but is seized.
I would pull it off and with the help of a friend hold it over a waste bucket and pull the lever in and see if the slave actually operates. Dont however pull the lever more than once otherwise you run the risk of driving the piston out of the slave.
Another way would be to put a plumbers adjustable pliers across it so that there is tension on the pin that pushes the clutch in, and slowly pull the level in, that should create tension on the pliers and you will be able to feel it.
Just an FYI, I spent half a day bleeding my ?!$)&(879@0 clutch to remove one bubble of air, and the clutch wouldnt work properly right up until that last feakin' bubble was gone....
As usual its most likely something quite simple, good luck.....