I'm not going to lie, I'm currently experiencing the same thing. I have an ACT clutch. Didn't do it immediately. For me started 5000 miles after installing the clutch.
I tried bleeding it the old fashioned way, adjusting hte clutch pedal, messing with the reverse lockout plate and it still does it.
I may use a vacuum pump this time to bleed the clutch. After that I may have to pull the gearbox out to check
