This may be related to a characteristic of the numerous slicers methods of handling single thickness walls. If your model's wall is of insufficient width, it "ceases to exist" in the slicer. Ultimaker's community forum has a reference that may be of value, second post to the linked page:
This is known. It's a limitation of how Cura calculates these things:
Your model outline is inset by half the line width. If anything
remains, it is printed with the normal line width. If nothing remains,
only the "Print Thin Walls" option may still save you. If two lines
overlap a lot, then one of the two will have its extrusion rate
reduced to prevent overextrusion. You'll ooze some filament there but
hopefully not too much since there is a backpressure from the earlier
printed line.
According to that same forum (and likely other locations on the internet), there is a setting for "print thin walls" that may solve the problem. The original poster discovered that it did not, for his model and had to increase wall thickness in the design software.
STIL
, rather thanSTL
or was that a typo..? I had failed to notice it when I approved the edit, but now I see it. $\endgroup$