The following settings are recommended up to Autodesk Inventor 2017 and NX 11

Inventor - System

• Only standard colors are transferred. Sub-elements of objects cannot be colored individually in the systems.

Inventor - STEP Preprocessor

• To export a STEP File please choose File -> Save Copy as.. and the STEP file.
• The translator uses as default file extension *.stp.
• The default setting for STEP export is AP203. For AP214 export you should always use the latest STEP standard. In this case AP214 IS.
• The export log file "filename.xlo" gives further information.

STEP File

• In the filename syntax special characters (especially / * % ) or umlauts must be avoided.

NX - STEP Postprocessor

• Start the external STEP postprocessor with Translator -> STEP AP214 and select Import.
• Select Edit -> Settings and define the options:
  (or interactive from NX 8.5) To export a STEP File choose File -> Import ->STEP203 or STEP214.
• Object Types: One or more of the options Solid, Product Data, Surface and Wireframe (depending on model).
• Recommended is to use the default settings in menu Translation Control (Tolerant Modeling).
• A*.log and a *.def file will be created in the same directory as the imported models. 
• Validation properties are supported.

NX – System

• Shaded view is helpful for a first impression of model quality.
• By choosing the menu option: Information -> Object -> Type -> Solid Body -> Select all correctly transferred solids are identified with red color. (Same way with other model types).
• By choosing the menu option Information -> Object -> Objects -> Select all after choosing the filter for Solid Body in Information -> Object -> Filters -> Type Filter correctly transferred solids are identified with red color. (Same way with other model types).