i know this is an old issue:
a simple box 28x80x30
_filletEdge with R14 on 8 edges would be my aim
(1) left - the _box 0 28 80 30
(2) next - filletEdge R14 2 edges consumes top face from 2 sides → works
(3a) trying to consume the same face, but with 4 sides → fail
(3b) same at buttom face → works 
(4) the 8 edges i would love to fillet, filletedge must consume 3 faces of the box 
(5) needed geometry - in this case a cleaned up filletEdge-mess, normally i build the needed surfaces - revolve and extrudeCrv for stuff like this…
kind regards - tom