Maybe someone will be able to tell you something that I am overlooking. But here are some thoughts.
- I think that the portion of the wiki page you see there just didn't get updated for LTI 1.3, and what that portion always said for LTI 1.1 remains. But it's not quite right regarding LTI 1.3.
- Do you have `$LTICheckPrior` set to 1 in authen_LTI.conf? If that is set to 1, then in my experience with D2L, the initial empty score for the assignment in D2L is considered equivalent to a 0 score. So a student's WeBWorK score being 0 will mean that student's score is not updated for D2L, and the blank score is not replaced with a 0. Then the problem becomes something else: a student who doesn't to the assignment at all, even up to the close date, will not get their score updated in D2L. So when a close date happens, you need to manually put 0s into D2L for those students.
- Once the grades are in D2L as 0s, I don't know how to clear them except manually clearing them using the Grades tool. Or I guess you could completely remove the External Learning Tool links and then the associated grade items, and re-create them.
- Grades are only ever passed back for sets that have passed their open date. If you have the entire semester's sets open from the start of the semester, the grades for all of them get sent to the LMS. And mostly as 0s since most students haven't started most WeBWorK assignments yet (unless $LTICheckPrior is set as mentioned above). If you change your sets to open later, say in batches on a weekly basis, this will be reflected in the grade passback as time goes by.
- You could consider hiding these grade items in D2L, and manually unhide them as the weeks go by. And also consider manually making changes in Manage Grades each week, updating how students' overall grades are calculated.
- You could revert to using LTI 1.1 and get the behavior that you used to have.
- If you are adventurous, you or your WeBWorK admin (if that is not you) could apply the changes that were made for 2.20 that I previously mentioned. These changes are here:
https://github.com/openwebwork/webwork2/pull/2617
I would not recommend this unless a person knows what they are doing well with git. I can't promise that this would work out well without also bringing in other changes that have gone into version 2.20.