I’ve installed the plugin, edited the template and it looks great. But when I wanted to tweak it and disallow a few uninteresting categories, related posts stopped showing, on all posts.
When I tried unchecking the checkboxes of the categories and clicked on Save Changes, nothing changed. I found out that if I leave one category checked, the rest are unchecked.
I am using Yet Another Related Posts Plugin Options 3.5b4 with YARPP Experiments 0.6.