Just a thought...did you bench bleed the master before mounting it?
I know on some years of Jeeps you have to either unscrew the pressure sensor from the combo valve or pull out a switch on the combo valve in order to bleed properly sometimes.
'94 YJ - SBC/AX15/231, SOA, 8.8, 34" swampers
'06 LJ Rubicon - 31" ATs, OME 2.5", belly-up skid, other junk
'75 CJ5 - 232/T14/D20, 'glass tub w/ 2" BL, otherwise stock