For a few weeks there has been an annoying stuck of hovercards, at random. When it happens, whatever someone does the hovercard does not close. Timeout does not work. The solution is to find another link and stay above it until a new hovercard is risen. After that, the bug behavior stops. This is a reason for someone to disable hovercards.
Topic on Talk:Page Previews/Flow
I would like to add my experience that even though the pointer no longer points to the link, sometimes the pop-up is not closing on time. I have to go again on the link, wait for the pop up to open and then close.
Bug tracked at phab:T92932