It's applying the 'hidden' tag to the pchild child comment block, which hides them all - https://i.imgur.com/wTCuWwH.png
I get off work in a little bit and will get on this
nice find!
I can see your comment reply in my inbox and vote on it, but it's not here at all.
polsaker fixed it - the deleted comment still collapses, but you can now expand it to see the children comments
Fixed. Next time please report bugs here.