I was attempting to FD PL some alts yesterday and it wasn't working. I remember this always being a thing back in the day, is there some reason why monk PL isn't possible on this server?
I'm not sure how we have it set, but I tried to give a pretty detailed explanation of how it used to work on live servers in this era (when it was mentioned in the past). Basically, if a mob enters flee mode and then you try to FD after, you'll still get faction hits and damage credit. You can root the npc and then FD, and it wipes your damage. I'm having trouble finding the thread where it was discussed on here, but I found plenty of posts talking about it working the way I described.
FD PL'ing should work good on skeletons and npc's that don't flee, Kurn's was a good spot for it I remember