Hi jetblast actually I guess that's not a "disappearing fillet" type case by default, but it still seems to be a corner situation that MoI's fillter does not handle very well. It needs the side face to be extended like this:



Then you'd need to use "variable radius fillet" to make it go to zero radius at the ends, in MoI that would be by expanding the "Fillet set" option and creating a new point set with 2 points one at each end with a zero radius on it. But since MoI has problems with that corner condition in general it's probably not going to work in MoI.

Maybe it would have better luck constructing it with a straight rising piece.

- Michael