Even if you aren't noticing glaring problems, it's a good idea to check on the health of your gradebook every now and then. With a few exceptions, issues in the gradebook are usually caused by other parts of your course. It's the canary to your course's coal mine. This means it's a great idea to check on it periodically while you go about grading submissions. Below are some possible concerns, their causes, and how you can fix them.
If an assignment is nowhere to be found in the gradebook, but you can see it in the Modules/Assignments tab, check its due date. Assignments need a due date to show up in the gradebook. You can also make sure that it's published since unpublished assignments can be hidden if you uncheck them in the View menu.
If it's in the Assignments, but not in the Modules, then you just need to add it to the Modules tab. To do that, click the plus + icon at the top of the module you want it in, then find the assignment in the list that pops up. That being said, it's best practice to create the assignment in the Modules tab to begin with, using the [Create Assignment] option in the screenshot below.
Totals column has an exclamation mark
You may also notice an exclamation icon in the Total column. If you click it, it will tell you what is off. For example, this is a warning that there is an Assignment Group in the Assignments tab that has no points possible in that quarter. That means there are no published assignments in that group that are set to be due in that quarter, which could affect the students' grades.
The Assignment Groups do not add up to 100%
If you see a column marked as "0% of grade," or add the percentages and realize that they are adding up to something other than 100%, that means you need to check your Assignments tab in the course. As you can see, these can cause the students to not get the grade they earned.
Whenever you import shared content, check the assignments tab for an Imported Assignments group. If the assignments are in an Imported Assignments group, you can move them one by one to your other groups, or move them all at once.
Crazy Total Percentages
Are there any Assignment Groups or Total Grades that are above 100%? That means you might've awarded one or more too-high grades at some point. It's important to keep an eye on the possible points when grading. See below for an example: The student got 100-points on a 20-point assignment, then 100-points again on a 75-point assignment. Even though they had others with normal grades, and even some missing ones, it pulled up their Formative Assignments to 164.17%, Summative to 100.98%, and their Total to 138.9%.
Canvas actually displays a warning when you accidentally award a too-high grade. However, it doesn't pop up if you assign just one point more, like 21 for a 20-point assignment. It has to be a sizeable amount, at least 150%. So you can't rely on it to catch smaller mistakes.
Completely Different View
Did you click around, and find that the gradebook looks totally different now? It might mean that you changed it to a different view. It's jolting, but has a quick, easy fix. You just need to find the dropdown that had changed it, and switch it back.
See below for each view you might get, with the dropdown highlighted in green. Just click that dropdown and select the regular Gradebook... option (shown above) to get back to the normal view.
Missing the Notes Column/Grading Period Dropdown
See this article for how to get those to appear in your gradebook.