DID YOU BENCH BLEED the master cyl before hooking the lines up? video here it's a must do for new master cyls.
XF brakes should be fine, when working. if it's a master issue, it will still be an issue on 6 pots, so you need to confirm that is the ussue.
My best method for bleeding brakes now (on my own) is to get a LONG piece of fish tank bubbler hose, or similar clear 1/4 inch ish hose (bunnings even sold it last i bought)and a bit of rubber hose that fits it tight and to the bleeder nipple.
and i basically pump the pedal slowly and if the fluid is all brand new you can even return it to the reservoir in a loop and keep pumping until no bubbles show. i'll draw you a fine picture with windows paint if you need an illustration. otherwise you need to keep topping up the reservoir to avoid sucking air when it's low.
do this for the 4 corners and it's been the only way i've been certain there's no air in the lines.
those suction one's haven't worked for a few people i know, so it's something you can try before going further.
A mate of mine just got a 1996 master cyl (original) from a wreck at the wreckers, it was clean so he's just fitted it and it worked.
20yrs ago i was blasted for using second hand good quality ball joints in something compared to new crap we are talking about here. which later i finally tried and they could have caused a serious accident (i tagged you but i'll link here also)