New Quizzes images not visible for most students — re-upload didn't fix it (May 2026 incident context)

Question

Hi everyone,

I'm an ed-tech administrator at a Brazilian higher education institution (SENAI CIMATEC) and I'm trying to understand a persistent image visibility issue we experienced during a large-scale exam on May 15, 2026.

Here's the full picture:

What happened:

* We applied a quiz via New Quizzes to the entire institution simultaneously
* A significant portion of students could NOT see the images embedded in quiz questions
* A minority of students COULD see them without any issue
* Instructors could see ALL images normally, both in teacher view and student preview
* No error message was shown — just a broken image icon or blank space
* When we exported the question HTML, the <img> tags were present and the URLs looked valid

What we already tried:

* We took screenshots of the original images and re-uploaded them manually into the course
* Re-inserted the images into the questions from scratch
* This did NOT fix the problem for most students

Context:

* The exam was applied on May 15, 2026 — shortly after the Instructure security incident (May 6–11)
* We are unsure whether the incident left residual CDN/cache instability that affected file serving for student-role users specifically
* We use Classic Quizzes migrated to New Quizzes format
* No Respondus LockDown Browser was involved

Our open questions:

* Is there a known bug where re-uploading images into course Files still doesn't fix visibility for students, even when the file is published?
* Could the May 2026 security incident have caused residual CDN or permission cache issues that persisted beyond May 11?
* Why would the image URL appear valid in the HTML source but still not render for most students?
* Has anyone confirmed whether moving images to My Files (user-level, not course-level) is a reliable long-term fix or just another workaround that breaks under certain conditions?
* Is there a way via the Canvas API to audit which file URLs inside New Quizzes questions are pointing outside the current course context?

Any insight from the community — especially from admins who went through the May incident — would be hugely appreciated.

Thanks in advance!

dbrace · Answer

@cpowell2, I cannot seem to get the link to your blog post to work.

I even tried to find it on https://www.canvasinsider.blog Substack but could not.

Can you reply again and include it as plain text instead of as a clickable?

Thanks!

-Doug

cpowell2 · Answer

Hi @RodrigoMacedo - I've had some communiques from students who can't view digital images in a Canvas quiz. When asking about their technology, some of the students were using Apple Safari on their macOS laptop or desktop. Unchecking Cross-Site tracking in the Safari settings allowed them to view the images. I wrote about it a few years ago in a blog post.

Hope you find a resolution to your issue!

Chris Powell

WWU Canvas Admin