Thread:M67PattonZippo/@comment-9605025-20170402223014/@comment-27345308-20170403113755

That's what happens when a thread is deleted through the normal MediaWiki way instead of through the thread deletion button. M67 replied on that thread, therefore creating Board Thread:General Discussion/@comment-Steven1210-20170401113110/@comment-M67PattonZippo-20170401144605 page. The Forum extension tried to find the parent page ID (Board Thread:General Discussion/@comment-Steven1210-20170401113110) but fails, and 0 is returned because that's the page ID of deleted pages.

Why the link partially works in another bug. Thread:KockaAdmiralac looks similar, doesn't it?

Oh, the joys of Forum... now you see why are they making Discussions. :P