[Infill Pattern is changing]

Oh nice - thanks for that!

[Infill Pattern is changing]

the infill is actually not changing at all, no matter what infill pattern i set in cura. 

i somehow found a workaround by adding 0,2mm thickness to the geometry. this gives me a nice overall concentric infill pattern.

 

i still don't understand why the software is doing this with the thinner geometry!?

[Infill Pattern is changing]

the infill in my print preview is changing between concentric and lines. i can see the result also on the printed part with some roughness on the surface. is there a way to avoid that infill change or optimize it?