Drawing a line creates a new hole

Hi there, I’m trying to draw a line here to split this green surface in two. The line should be on the grey surface. At first, I tried to intersect the grey and green surfaces, which created most of the line I wanted. However, this left a small gap. So I intersect the faces again hoping the rest of the line would close the gap.

The line gets created, but then a hole is also created.

If I don’t use the intersect faces and instead draw a line, the same hole gets created. Not sure why this is happening.draw line creates hole.skp (5.2 MB)

That’s not a bug. It’s due to the exceedingly small geometry you are trying to create. SketchUp won’t create faces with edges that short. A human hair is in the neighborhood of 0.04-0.1mm thick so this is less than a hair.
Screenshot - 3_8_2020 , 3_48_55 PM

You could scale the model up by a factor of 100 or 1000 and get it to fill.

Or rework the geometry to avoid the need for such a short edge.