When l switch the subdivision surface from Catmull-Clark to Simple, half of the object (in object mode) stays smoothed and half sharp edged. It is not pentagon as in the video. Is there any setting to solve that?
Here is the screenshot of an issue.
Hmm. That's really weird.
Have you tried deleting that pentagon and starting fresh with a new one? It may be that the geometry got modified somehow. If that's the case, then a creating a new pentagon and working from there should solve your issue.