There are multiple possibilities here that might explain why Canvas would think that you still have assignments that need grading:
- Double-check to see if there are any students who actually do need grading.
- Are there any students who re-submitted after you already graded their assignment (you can tell because the check mark on the SpeedGrader page will be yellow, instead of green).
- Has "Test Student" been graded?
- If the Assignment is a quiz, the student may have an Open Attempt -- this will never show up as being graded.
- If this is an Assignment where the student has begun something to resubmit, and then never actually submits, this will never show up as being graded.
I'll keep my ear to the ground and keep you posted if I get anything else on this topic!!!