In v4.0, in the post area the results below "Use the search box below to select related items" don't show up, even if posts were already set as being related using 3.0.1.
Doesn't work in Chrome 18 or Firefox 11 or 12.
When downgrading back to 3.0.1 none of the posts set as "Related" display, even after clearing cache. Had to restore database to get Related script to work again in 3.0.1. Not good.