CATIA Shell Issue

Good morning,

I have a part that I can normally Shell in my CATIA V5R20, however, when I put the same part in CATIA V5R21, I get the following error attached to this message. Does anyone have any idea what it can be? I am also attaching a picture of what it is supposed to look like and the step file in the state just before the shell needs to happen.

Any ideas will be much appreciated.

Thank you very much.