Did Instructure update Canvas RCE or style standards?

Question

Overnight, from 5-14-26 to the morning of 5-15-26, Canvas pages are behaving differently for us.

Video embeds are getting "squashed" when the RCE is opened and, if the page is saved, they continue to look that way. Also, in a breakout box, I notice it eliminates position: relative, which was on the Allow list, amongst other style values.

What, if anything was changed? Can it be made backward compatible? Do I have to change all of my institutions video embeds now? Is this a feature not a bug?

Thanks,

Chris

abrgomez · Answer

We don't use DesignPlus, so it has to be something from Canvas side.

From what I'm seeing in the inspector, Canvas uses TinyMCE for its editor. I'm not sure it's a bug with the library itself, maybe it's an issue with how it's configured by Instructure. But regardless I don't think there's much we can do from our side.

chrisream · Answer

Thanks for the update, @abrgomez. Very similar issues here.

By chance, do you use DesignPlus from CidiLabs? I'm pursuing support from them as well. I was just wondering whether that is a common thread in our development. This issue arises on pages where their controls haven't been used as well, which makes me lean toward Canvas.

It feels like it's part of a vendor's JS … somewhere.

Good luck!

Chris

abrgomez · Answer

@chrisream My bad, I didn't see this post before!

Indeed, something's up with the way the RCE is processing the "position" style, along with related styles like "top", "bottom", "left" and "right"

@Jeff_F For example, this is how an iframe that uses the "position" style looks like:

But as soon as the RCE editor is opened, the styles are removed. If the page is saved without adding the styles back, this is how it will look like:

Note: I'm using a youtube video as example, but the embed code Youtube automatically generates does not use the "position" style, so this won't be an issue in those cases. But there are other video/interactive services that include these styles as part of their standard embed code, so this will be an issue.

I'm leaning towards this being a bug, not a feature, given how the removal behavior is very different from how the RCE handles all non-whitelisted styles/tags.

I've already reported this through my institution support contact, but it'll probably take a while to get to the developer team since this is not a very noticeable issue since already existing content still works, and it only shows up while/after editing.