At the bottom of the webpage for each instance is a link that says "Instances" If you click on that it shows all of the instances that are federated first. Then below that is the list of blocked instances. Easiest way to look is by doing "ctrl + f" and searching for "blocked" and that will normally get you to that list the fastest.

You can see this list whether you are a member or not of that instance. You just need to make sure you go to the actual instance and are not viewing it from your "home" instance account.