Embedded PDFs not rendering, consistently #2224

I'm not sure if I'm getting my terminology right, but often when I try to view a PDF that is embedded in a webpage, it ends up looking like my attached screenshot. I use learning management software (Brightspace), and it consistently happens with that. It doesn't happen on any other browsers, including Chrome or Firefox.

I just noticed that that same kind of colored barred image is showing up for the image uploading of this very form.

I've tried turning off Enhanced Tracking Protection, allowing "Extract Canvas Data", and turning off uBlock Origin, but the issue persists.

Would you mind trying to enable webgl?

I am having the same problem. I checked the box to enable webgl in Settings and restarted LibreWolf but I am still getting the vertical striped pattern when I attempt to view a pdf file in Brightspace. Any further suggestions?

I am having the same problem. Has anybody found a solution yet?

Allow Canvas: (Don't). https://librewolf.net/docs/faq/#should-i-allow-canvas-access-how-do-i-do-it

Further Information from Tor Browser https://forum.torproject.org/t/problem-in-the-images-that-i-download-or-try-to-upload-somewhere/15075

@Sazu-bit The issue description mentions that 'Extract Canvas Data' was already tried.

Could someone link me to the offending PDF if at all possible... or 'an' offending pdf. All the PDFs I'm locating work just fine and the Site by Site canvas blocker permission is working just fine.

(My guess would be that this is an iframe which implements a custom pdf reader using canvas and the canvas permissions don't play nicely with iframes)

If this is helpful, I tested the same pdf file (1) by attempting to open it in Brightspace using LibreWolf and (2) by downloading it and opening the local file in LibreWolf. The same pdf file failed to render properly by the first method and rendered properly by the second method.

Caveats: I have enabled webgl but have not allowed Extract Canvas Data because I do not have the Manage canvas extraction permission icon to the left of my URL. Also, I could not find an Open File menu option within LibreWolf, so I opened the file from the Files tool using "Open with other application." (I am using LibreWolf 138.0.4-1 on Pop!_OS 22.04 LTS.)

I hope that helps.