Hi Alex, STEP is a complex format and there are all kinds of different ways that things can be configured.

For example a planar face could be exported as a specific "PLANE" entity type, but it could also be exported as a generic NURBS surface. It could represent a reversed normal direction by setting a reverse flag or it's possible to flip the geometry itself and not set the flag. Various things like that.

It sounds like your receiving application doesn't like to handle certain configurations. It may be difficult to figure out exactly what it's sensitive to.

First of all, what type of objects are you sending through step format, is it curves only? If not then you must be doing some other stuff in SolidWorks since the DXF transfer will just send curves over.

If you're sending solids, one thing I notice in your Solidworks settings you have "Split periodic faces" set to be on. Periodic means a smooth closed surface, that would correspond to the moi.ini setting
[STEP]
ExportSplitClosedSurfaces=y

So the first thing I'd recommend trying is to set that option in moi so it will be treating closed surfaces similar to SolidWorks.

If that doesn't make any difference then the next level of investigation would be if you had the simplest possible example that works from SolidWorks but doesn't from MOI and send the .3dm file and both the STEP files out from MOI as well as the one made by SolidWorks so I can try to examine them and try to see what is different between them.

It will make it easier if there is not a lot of stuff in the file, the simpler and fewer pieces the better for this kind of analysis.

Thanks, - Michael