The screenshot shows comments somehow being nested multiple levels without an intermediate parent. That's a bug, right? Nesting should only be increasing by one level at a time.
I've observed this happening a ton across many different threads. There's also some weird cases where the top level comment is just a link to "show parent" and... It's not actually top level??
It's bugged. Change your default comment sort to 'New', fixed it for me.
Hot works for me, top doesn't.
I believe Top is completely broken, Hot is sometimes broken. New works.