On my blog, blockquote is now not working at all via the button in the visual editor toolbar. The button just doesn’t respond. This is in all browsers on a Mac. Has been the case off and on recently, and today looks permanent.
@davidderrick, that sounds like a separate issue. Can you please try refreshing your edit page and trying again and also check to see if the same problem happens with an alternate web browser? Once you have done that, please post a new help request with all of the details at https://en.forums.wordpress.com/