Hello, Im confused about this bug.
you can visit the category from here
AI-generated summary
A user reported that topics disappeared from a category named “ad” on their Discourse site. Lilly asked for clarification, and Canapin discovered that the issue was likely caused by an ad-blocker blocking elements due to the category name “ad.” After testing, it was confirmed that the ad-blocker was hiding the topics, and renaming the category to “sh3ll” resolved the issue. inj3ct0r thanked the contributors for the solution.
I notice two things:
https://sh3ll.cloud/c/ad/68.json shows there are 5 topics in this category.
But the category is named “ad” and I supposed it could be because these topics are advertisements removed by a browser ad-blocker.
On my default browser which uses an ad-blocker, I see no topics on your link, exactly like you.
Using Safari, which has no ad-blocker by default, I see the posts:
I’m not 100% sure this is the cause, but if it’s not, that should give enough clues to help pinpoint the exact cause 
edit: oh, I replied but apparently didn’t see the screenshot in lilly’s post 
edit again: that seems to be the issue:
My adblocker adds a display: none !important; on these elements:
I think many adblockers look for the “ad” word. Using a different name for your category may fix the issue.
yea but unlike mine, your reply was actually helpful 
Damn!
it works fine !
I didn’t even close to this solution!
I Changed the slug from “ad” to “sh3ll”.
Thank you alot and now it works without any problems. 
again @Lilly Thank you for help lily