See the structural frame pictured as an example. This was created using the "structural member" feature. We use this almost daily to produce frame weldments. The issue we find is that the tubes that are diagonal often get rotated in a way that prevents the end miter cuts from being properly formed. The feature is being driven by a 3D sketch and I can say with certainty that there are no issues with the sketch that would be driving this (i.e. sketch end points not coincident with terminating lines, non-square frame geometry etc). 

I'm pretty sure this is a common issue and the only way I've been able to resolve this is to play with the alignment angle in the structural member feature dialog. However this is often very time consuming/iterative and in fact often times just won't produce the desired result. 

Please help me figure out how to definitively resolve this issue!