Using CS5 here and it's stacking. www.northtexaslakesrally.com/ I used it on my personal site and it worked fine.
Also, when I used the social media dialog box when inserting it wouldn't accept the OK button. I had to hit cancel to get the window to close.
Worked fine on my site here though. www.thegraphiclibrary.com/
The only real difference that I'm aware of is that on the site where it stacks I have the css for that to justify to the right.