Variables Blocks Disappeared

A student of mine was working on a Snap! project when for some reason the variables section just went black. She can still find and use those blocks by searching for them from another window but that particular window is just black. We tried:

• Turning the computer off and then on again
• Exporting the project and then re-importing it to another user's Snap! account

Despite all of this the problem has persisted. Here is the link to the project.

If anyone has any idea why this might be happening or how to fix it please let me know!

Welcome to the forums!
I think I know the problem, this happened to me too in the past:

Sometimes the category disappears when you use an apostrophe in a custom block. This is due to the fact that Snap! uses apostrophes internally to compile blocks and it messes up the rendering.
The only solution I know of is to export the XML, remove the apostrophe, and import it back to Snap!.

Or she accidently hide primitives, try to right click on the black and select show primitive...

(if you right click and it show hide primitive: the problem comes from elsewhere)

did you even look at the project?

it looks like this

and you can't even right click there.

Sorry, i don't see the link, but anyway, it's an april fool prank !

It isn't.

yeah, it's not an april fools prank.

Yet, I cannot reproduce this bug in a different project, which is weird.

What was the problem dardoro ?

As helicopur said, ' in the block name
. word "card's"

To reproduce it you just have to make a block like
test' %name