Creo (and before that Pro/ENGINEER) has always represented cylindrical surfaces in this manner. It is a core feature of the software. That's just the way it is, to the best of my knowledge you can't change it.
Refer to this: www.ptc.com/en/support/article/CS19238
Which states as the "Resolution":
- Works to product specification for Pro/ENGINEER and Creo Parametric
- Note:
- Extrude as Surface will create a single piece cylinder
- You can Copy > Paste both halves into a new single surface
- You can refer to Product Ideas @ PTC Community and consider posting a new one
- This is how cylindrical surface are created in Pro/ENGINEER & Creo Parametric
- Creo Parametric does not create full periodic surfaces; it always splits them in two (i.e. for cylinders, spheres, cones, torii, surfaces of revolution, etc)
- This behavior should not impact any workflows within Creo
- When you apply a draft to a cylindrical surface, selecting one half surface patch will apply the draft to the full cylindrical surface
- When you apply a color/appearance to a cylindrical surface, selecting one half surface patch will apply the color/appearance to the full cylindrical surface
- Same for applying loads/constraints in Creo Simulate
- If you find a workflow in Creo that is impacted by this behavior, please open a case with technical support
