Who here has used a Powertrain Technology hydraulic throwout bearing?

I have a 10 year old Keisler Engineering trans with the jyd TO bearing and two years ago it started not wanting to shift in gear. Turned out to be the master cylinder; fluid was leaking past the seals. Got a rebuild kit and issue solved.
Your case is similar in that there's not enough hydraulic pressure to fully engage the TO bearing. The master cyl might not be matched to the slave cylinder or the seals are leaking. I would start by calling tech support, giving the specs of the master cyl to find out if it's compatible with the TO.