ISSUE with duplicating course with custom fields

Good morning,

I don't know if this is the right place to report that, unfortunately, 
Moodle seems to have some issues duplicating courses when unique custom fields are required.

We've been struggling with this problem for months, forcing us to duplicate courses 
from the CLI, until today we removed the uniqueness of the only custom field for the course we have: everything returned to normal very quickly.

Unfortunately, however, this problem doesn't affect all courses: courses in older categories, 
prior to the creation of the unique field, continued to be duplicated. 
Courses in newer categories did not. I don't know why.

Can you check? I see often a lot of problems duplicating course and I think this can be a real
game changer if you confirm the problem

Thanks in advance.