If anyone tried to get a Tekla file into Alibre, or a CIS/2 file (which end as .stp), seems not work.
Also if 3d dxf can be imported? in the future maybe...
Alibre has no support for 3D dxf or dwg.
You might try some of the online viewers to look at the stp file to see if they can handle it. (if IP rights allow)
I wonder what happened to all the SYCODE addons and their code? Didn't they have one for 3D dxf? I know SYCODE was purchased by the 3D Systems and then it vanished.
IDK if you can still get their addon from somewhere or if it will even work.