Thanks Burr - maybe the curve fillet solver gets confused by this particular "exact anti-tangent" type configuration.

If it is in the solver, that's an area of the geometry library that is not very easy to tweak with though.

.... although maybe something else is also going on because separating it out and 2 pieces at a time seems to work ok, I'll put it on my list to check out, thanks for posting it.

- Michael