Go to Settings on the iPad/iPhone
Find the Safari app (you can type it into the search bar on the top)
Open it
Toggle OFF 'Prevent Cross-Site Tracking' (it should be grey)
Go back to Settings
Find the Student Canvas app (it appears as 'Student')
Open it
Toggle ON 'Allow Cross-Website Tracking' (it should be green)
Now go back to the Student Canvas app. Images should now appear.