Hi Renato, do you have a .3dm model file of one of the shapes where the fillet did not work?

If you could post the model file, that would help a lot to give you a better answer.

Fillets are a sensitive and finicky area, there are a lot of things in a model that can prevent fillets from being calculated properly.

Sometimes it is a matter of asking for too large of a radius than will fit. Often times it is surprising how much room a fillet of say radius 1 or 2 will fill up. If your fillet does not work, try using a smaller radius to see if that will work. If you have little faces that the fillet would totally consume, that will cause the fillet to fail and you need to use a smaller distance.

Also if you have an area of tight curvature, that can limit the size of fillet that can fit there.

If you have a corner junction with many many edges coming together at a single point, that can prevent fillets from working because MoI's fillet engine does not handle every single kind of corner junction.

If you have surfaces or edges that loop back on themself and "self intersect" then that can prevent fillets from working.

It is impossible to say which of these or other problems you may have run into without actually examining the model. There is a good chance that you just ran into a fillet bug as well, I am just about ready to apply an update with some fillet bug fixes for the v2 beta, so I think that should help out in this area.

- Michael