Problem:

When viewing courses, assignments, or quizzes in MyClasses while using the Safari browser images are not shown or are shown as a question mark.  

Solution: 

On your Mac in Safari select Safari > Preferences > Privacy.

Uncheck the option "Prevent cross-site tracking"

Restart the browser and try logging in again.

Note: Safari 13.1 contains an update that may cause issues with downloading files, chat alerts, and displaying images in Canvas. Canvas engineers are currently working on a solution for this issue. Until then, you can avoid errors with files and images by
disabling cross-site tracking prevention in Safari when using Canvas."

If this does not resolve the issue you can try another browser(ie: Google Chrome) to see if the problem persist.