I'm relatively new to Canvas myself and have yet to see anything like this but I'd like to see if I can help as it looks like a permissions/access issue to me.
Q1 - Where are the images stored? I assume that they are not stored in the same files folder of the course/section as the home page on which they are displayed?
Q2 - Which user(s) sees the padlocks instead of The Chick and The Grinch? Do they/you(?) have direct access to the images in whichever course/section they are actually located?
Hopefully these questions should be enough to get the ball rolling on this.
firstname.lastname@example.org, email@example.com has asked you the right questions! Welcome to Canvas, both of you. Generally speaking when I've seen this it's because the teacher has linked to images that are located somewhere the students enrolled in the course can't access. For example, the image files might reside in a different course, or she might have uploaded them to her personal files space, rather than to the files area of the course itself. Also walk the teacher through her image embed process: did she use the Content Selector panel on the right side of the page to select the images from her course files? It's also worth checking the Files area of the course itself to make sure the images don't have a grey cloud (unpublished) or brown cloud (restricted access) appearing next to them. Check these variables out first, and let us know if it solves the problem.
From personal experience, I think that stefaniesanders suggestion that the image files might be unpublished/restricted in the files area is most likely. Additionally, if you have your files area sorted into folders, check that the folder itself is also published. For example, see my attached screenshot - I have two folders in my files area, and the folder called "Images" has a grey cloud showing that it's unpublished. Even if individual files within the folder are published, they won't be visible to students until I also publish the folder.
firstname.lastname@example.org, it's been over a month since we last heard from you. Did any of the responses above resolve your issue? And if not, were you able to find a different solution? For now, I will mark this question as "Assumed Answered"; however it will not prevent you or others from responding. If there is a workable solution posted here, please mark that answer as "Correct." Thanks!
I have a similar issue, i.e., I've uploaded a .jpg file to my instructor page and when i switch to Student view I see the following
I've tried the posted suggestions w/o any resolution. Any other ideas. Thanks. Uche.
Update - Problem solved. The file associated with the .jpg image was not published and once published the image appeared. By default the .jpg image file was placed in /Files/Uploaded Media folder. Thanks.