It seems that the index of the primary key is recreated in the rebuild table script, but the corresponding constraint is not.
I checked the function again in version 13.1 and there it works as expected.
Dirk
Thank you Dirk. I made some changes a month or so ago to create PKs in Generate Schema Script immediately after the tables (to fix something else), and inadvertently broke this at that time.
It is fixed for next beta.