PROBLEM RESOLVED:
Yesterday i pulled the wheels off to inspect my install and ensure everything is how it should be. Upon inspection i noticed that there was a gap between the piston and pad (approx 1mm) on both front calipers (side note: the front calipers only have one piston per caliper)
When pressed on the brake pedal some of my pedal travel was being used to compress everything and fill this 2mm of freeplay (1mm x 2 sides). When I released the pedal and everything would relax I would then see the piston getting pushed back that extra 1mm - this seemed strange.
I removed the caliper to inspect and noted the the 3 spring steel legs that come off the back of the pad didn't sit correctly in the groove on the ID of the piston. Looks like the legs ever so slightly too deep and when i let go of the pedal the legs want to fall back into this groove and during this process it pushes the piston back 1mm.
Pretty sure pad numbers and parts all match up but looks like bending the legs ever so slightly will resolve my issue
So I basically had a mechanical free-play issue, not a hydraulic one
The silver lining? I now have one of the best-bled 850s in Victoria :-)
