I think this is common with unibody bindings. Probably why they created the EST system. The reason I got rid of my Cartels was because I couldn't center the boots without the discs turned sideways, which obviously limits stance options to what ever the inserts fall at. I had the same problem with my Flux.
Now it appears that the smaller re:flex disc limits the adjustment range even more so.
I'm not sure why they don't spend more time on their disc design. Even ride includes multiple offset discs to rectify this issue.