I just discovered that on my website I cannot do multiquotes as admin. It always stays on "Quote 1 post", regardless if you click on the plus icon on other posts. I logged with a normal user and everything is OK. Can someone else confirm if there is a problem with admin multiquoting before I submit a bug?

Works for me here.

Do you see any errors in the JS console? 

I guess you should submit a ticket so that we can take a look 🙂