Not sure if it's just my end but addons page slow to respond and when you manage to get it loaded, you either can't access addon details page or nothing comes up with search results. I might play around with one of the other browsers in the interim.
try to restart browser or pc>are you using any content blockers from the browser>are you using any systemwide content blockers in your operating system>are you using using filtered dns>try unfiltered dns>does your router do any type of content blocking?