I've edited (overrided is the term if I'm not wrong) one grade in the gradebook (the grade belong to one assignment).
I've changed it from 70 down to 45.
Then I've visited the assignment page, looking for grades and I see one 45,00 grade, while the rest of grades have one xx / 100 format.
Just guessing if:
1) the assignment way of displaying grades should be respected, by showing that grade as 45 /100
2) Something in the assignment should show that the grade is a overridden one
Two images attached, showing the gradebook with the overriden grade and the assignment itself.