But also found that outW parameter doesn't apply when generating mask. You may want to check.
And I found that rounded B-mask generator doesn't go well with Fusion 360 on 'some' slits. I don't know what makes some slits are left unselected for extrusion.
The outW option seems to be working in my environment.
The problem with fusion360 may possibly be caused by the use of elliptical arc curve commands in the svg path for the rounded pattern.
For example, I wonder if it would help to import the SVG file from the generator into Inkscape, export it as DXF, and then import the DXF file into Fusion360.