I wonder if a lot of these weird issues are down to the type of stl file ?

There are 2 types that I know of: binary and ascii.
had a problem importing an stl file into openscad yesterday. Loaded into simplify3d and saved as binary stl and it loaded fine into openscad after that. Presumably the original was ascii.

Does seem odd that different programs can 'see' stl files quite differently.