List items not moving when an item is expanded

Here is the bug:

Steps to reproduce

I have absolutely no idea, other than that this happened one time.

Expected result

What do you expect to see after carrying out the steps above?

Environment

Chrome under Windows 10


Additional information

This has only happened to me one time, so I guess itā€™s rare and non-urgent, but I thought Iā€™d show it here anyway, in case it happens to other people more often. I refreshed the page and the bug went away.