Potential Reasons:
1. The category you have selected may have either been removed or merged on our database. This was common last year when we first launched and were still making quite a few changes to our site structure. However, this should no longer be an issue, assuming you’ve updated your category selection.
2. Our server. We rarely experience any downtime, but if you notice an error with the plugin, try visiting Quotery.com to see if the site is loading properly. If it is indeed a server issue, the problem should be resolved within the hour.
If neither of these reasons appears to be the issue, please post here along with the specific category you have selected and we’ll look into it.