First of, don't fix it if it isn't broken. But subcategory behavior is terribly buggy, and with buggy i mean counter-intuitive. So I would consider that broken (or unfinished).
So I had this family for a steel column which is set in the family to subcategory 28_staal (dutch). In the project environment when creating an in-place model with category structural columns and the same subcategory, this object displays according to its subcategory as it should. But in the same view the column family follows the main category settings instead of its assigned subcategory.
Ofcourse there might be different ways to get similar/same results with filters ie., but this is not the only situation where you get unexpected/strange results with subcategories. See an earlier post I made about lost subcategory settings when cutting objects: https://forums.autodesk.com/t5/revit-architecture-forum/subcategory-change-when-cut/td-p/9056572 . This really shouldn't happen, also when joining it's the same.
