2.7.2 Advanced Marking (Rubric) Grades save inconsistently

Rubric marking has been double-checked for completion, Feedback Files show as saved in "Grade all submissions," as do Outcomes and comments. But the grade is not showing there, or in Gradebook.

Any ideas why? It's happening inconsistently: some grades save, some don't.

Here's a screenshot of one student I've regraded twice, still with no grade showing.

Strangely enough, I just tried re-grading by changing the rubric mark for one row, and this time the grade does show. Still seems wrong--and something I don't want to advise for teachers looking forward to the rubric scoring. See here:

**UPDATE**: After re-grading another student, the score for the student above disappeared:

At a loss. Any ideas?

Thanks in advance.