It only happens when you edit the post (EditComment).
Also, your "render view generator" strips the "border" attribute from "table". When edit, it's there, just not there in render view.
I've noticed too that threads disappear if you edit the initial post. I'm just curious: where do they go to? Is there some magical land of missing threads playing together? Are they kidnapped and sold abroad? Do they end up in Bolgia 8 of the eighth
circle of Hell where the fraudulant advisors are encased in individual flames?