What size bindings and boots? Any pics? I know you said they were centered but objective eyes might help.
I have the 390s and targas. It felt soo much better when I put the front straps towards the rear. I have size 10 boots in the l/xl bindings. I've felt that wash out feeling towards heelside before. I rotated my binding plates and it felt much better. Maybe the combo of moving my straps helped as well? Not sure..
I know you said the boots are centered in the bindings. Does that also mean your feet are centered on the board edge to edge? I know, dumb question but just making sure.