掲示板 Forums - Can't see reply to a comment made in a sentence

Got this notification that someone left a comment reply to a comment that I left in a sentence:

But when I click on it there are no new comments or replies:

I had this happen before but I thought "maybe the user deleted the reply or something", but this is twice it's happened so I'm a bit inclined to believe it might be a bug.

To notice, I've only had this happen when it is a reply to a message that's a reply of a message; when someone replies to a regular message I can see the comments just fine.

Tried this both on a Firefox browser (on desktop) and using the renshuu app on Android with the same problem.