[Gmsh] Bug? Error: Control Points not Cocircular

[Sebastian Theilenberg]

Hello everybody!

This is my first question to this list, so go easy on me! ;-)

I created a sphere using 8 Circles of 90 degrees, two creating one arc
of 180 degrees, and four of that rotated 90 degrees around the z-axis to
create the whole sphere. Then i created 4 additional Circles in the
x-y-plane to get an "equator". I then created Ruled Surfaces and
Volumes.

Everything works fine as long as the central Point lies on the z-axis.
If I move it to e.g. (1, 1, z) i get error messages complaining the
control points would not be cocircular.

My question is: Why is the creation of Circles sensitive to the position
on the grid? Is there a way to get it done nevertheless?

Thanks for any help in advance!

Sebastian