Good evening, @milessushi ...
I believe you'll want to check your "Notifications" screen to see if you have a specific notification configured correctly. You can set notifications for your entire Canvas account (so that they apply to all courses), and you can set them for individual courses that you are enrolled in. Here are Guides for both:
On your "Notifications" screen, I believe the setting you'll want to review is the "Submission Comment" row (listed under the "Course Activities" heading). If you hover your mouse over the words "Submission Comment", you'll see a small pop-up info banner which shows some additional information: "Assignment submission comment". Do you have this notification enabled for your Canvas profile?
One final resource for you related to this is found on Canvas Notifications - Instructure Community (canvaslms.com). Slightly more than half-way down the screen, you'll find a table with a red banner for "Submission Comment". That table and the one immediately below it give some further detail on this particular notification setting within Canvas.
Hopefully this information will be of some help to you. Please let Community members know if you have any other questions about this...thanks much!