To reproduce...

1. Create a course and add a teacher and at least one student
2. Create an Assignment in the course and leave all settings as default except enable 'Blind marking' and (if required) disable the two dates
3. Log in as student and submit something
4. As teacher note that submission is 'blind'.
5. Use the dropdown to reveal identities (note that this has worked - the name is shown)
6. Use course reset and remove all student role assignments and reset all possible assignment options
7. Assign a new student
8. Blind marking is still set to 'Yes' but the marking is no longer blind.

This probably seems an obvious result in this context, but teachers reset courses each year probably not having used an assignment for months. Their expectation is that it will work the same way it did the first time after they have reset the course for the next year. It doesn't. You have to delete the Assignment completely and recreate it. Unfortunately, staff don't realise this until someone has submitted and it's too late.

This usually amounts to data loss (having to start again) so it's doubly bad.