Weird.
Clutch arm, and actuator cam pushes the bucking bar et al over to the RIGHT.. That's how it separates the clutch plate from the clutch pads. The only thing that is further right than the clutch plate is the clutch COVER. Remove it and see what happens. Maybe the plate was hitting it? IE maybe the clutch seperation is way more than necessary, it only needs to separate a bit. Hold lever in and tighten the flower nut down further, all the way and then back it off until there's only a small amount of separation.
Also as Al Fisherman says in this thread.. Something could be hitting the cable mount post (thing in the centre that your cable outer ends at) so take it out and operate the clutch arm by hand just to test. If that works you can put it back in but with it's locking nut moved down a bit so it doesn't go in as far this time.
Doesn't explain why it was fine before. Is the tiny flower nut locking screw missing?
Let us know how it goes.