Corner printing.

[vapvap]

I am trying to calibrate the printer, but I can’t get a good print of the corners.
While it turns out this:

Tell me please, is it possible to fix this?
Regards.

(Slicer: Simplify3D)

[Phaedrux]

Try a different z seam setting in simplify. It looks like it's spreading it between all four corners.

[dc42]

Also I think you need to enable and calibrate pressure advance in the firmware.