That's not good. Can you please share what page you were trying to save? Also, can you please share the extension version number? Should be at least 4.0.75.
EDIT: This page works for me but only when I wait for it to load completely. Even then it takes a really long time between when I click the icon and the grid of images that can be saved to Pinterest comes up. When I look at it with a Web inspector I see that there are quite a few network requests and warnings in the console, which can interfere with the extension logic.
I know this isn't a great answer, but in cases like these it's usually best to use the hovering Save button. Sorry about that; if this is your page I will be happy to chat more about what may be going on.