I'm gonna take an educated guess & suggest the ball bearing is missing.
It goes between the clutch push rod and the slave cylinder piston.
Part of #37 in the KTM parts book. it may be (usually is) stuck in the grease of the slave piston, or perhaps on the ground now. Most bikes have them, it's a common thing to overlook.
If not, it's bleeding. SO many customers have brought me bikes "Oh, it's bled perfectly, no air, etc..." when it fact it isn't.
950 Adv 'S'
'87 KLR650 - <200K miles
"Like the Energizer Bunny, just keeps going & going..."