MeshCurveIntersectionBug.3dm (564.1 KB)
Here is a mesh and a polyline. They intersect, but Mesh | Curve Intersection is saying they don’t. I have run into many instances of this. Strangely, Mesh | Curve intersection is not exposed to Rhino, so to replicate this, It is easiest to use the Grasshopper Mesh | Curve node.
Simply translating both geometries (by the same distance) fixes the bug, further confirming that it is in fact a bug.
If anyone knows of any work arounds, that would be great. Also, I think it would be great if this Mesh | Curve intersection were exposed to Rhino.
[EDIT]:
I found a solid work around: moving the line by a smidge (0.0001, 0.0001, 0.0001). This leads me to believe that there is an issue with boundary conditions on Rhino’s acceleration structures. Just a guess. Or perhaps the issue is the edge case where a polyline intersects with a triangle at one of its vertices. Just some educated guesses. It would be great if this could be fixed 
Thanks in advance Rhino Devs.