Everything fine now after reworking the curves.

Dealing with filleting I realized that it is not possible to round with a perfect circle - for example if
you have a distance of 2,00 it is not possible to fillet with radius 1,00 exactly but a bit smaller than
the radius needed for a perfect circle.

Is there a specific reason behind it ?

Hi Tom, the fillet will fail if it would cause a face to be entirely consumed away as would happen in that case. The fillet engine does not currently know how to handle that type of case.

- Michael

Ok good to know, I had speculated that I may have made a modelling mistake.