Hi PaQ, the filleter in general has some difficulties in the "disappearing" fillet cases where the fillet kind of narrows down and ends in a single point.

That problem will probably take a fair while to get improved.

The blend problem I think is something different though, that looks like a tangent value is not getting scaled up properly like it is getting for the Blend command instead of Fillet. That one may be something I can fix up sooner, I'll take a look.

- Michael