AdBlock/uBlock issues (not sure if right place for this)

Upon sending someone a link to a page on this site, they informed me that they got the following pop-up on attempting to view the page: https://cdn.discordapp.com/ attachments/200648678380142592/439542730868391956/unknown.png (remove the space, I'm not sure how to get this as a link and not as a hotlinked image)

They did have an ad blocker on (specifically uBlock Origin), but this page-blocking popup stayed in place even when ad-blocking was disabled, or with a different ad blocker (Ad Block) in use. No combination of those, whether with Internet Explorer or with Google Chrome, removed the pop-up or allowed access to the page. According to this person, the page loaded completely, and then was replaced/blocked by the popup pictured above.

Another person who is a regular browser also told me they saw this, under similar circumstances. It is unknown if they tried disabling their ad blocker.

If I log out of my account, as I have Ad Block on my browser, I get messages indicating that I should allow ads or buy an ad removal pass, but these do not block access to the page itself, nor do they cover the whole screen.

Does anyone have any idea what is going on here? And if this is not the correct place for this thread, can it be moved to whatever the correct place is?

edited 27th Apr '18 3:07:35 PM by Technetium

That's the same message I've been seeing on my computers at work. The one descried in the other thread, the one that was just locked. And to emphasize again, I saw that message in all browsers, regardless of whether or not there was an adblocker installed, and regardless of whether or not I disabled it.