“not in the model” can mean several different things (there could e.g. be inverted faces that look fine in a software 3d viewer but confuse the slicer when it runs making it add weird cuts or creases).
First, run the .STL through Free online stl repair tool and post the hole log in this thread (i.e. the text that appears with black background). Usually downloading the resulting file (XYZ_fixed.stl) and running it through Luban should solve the issue.
If this does not help, recalibrate the extruder and print with a lower speed.