If you could post your gcode we could take a look at it and see if there is something in the code. I'm very curious about this since you say that you sliced in Cura and print in S3D works fine, slice in S3D and run in Cura host results in a slanted part. That is a good test (along with your other permutations on this) and points to something in the generated gcode or an interpretation (including accelerations, speeds, etc) of it. Recently, a friend had an odd issue with another slicer that was inserting code that caused his hot end to careen off in the -Y direction after printing 37 layers. It was very consistent and only occurred on this one part using this slicer. I figured out the issue and it had to do with his source geometry (STL file, Scott). An odd situation with triangles (6 "almost" equilateral triangles
were causing the slicer to act irrationally since it interpreted them as planar when in fact they were not - a rounding error.