Closing Acrobat Reader Kills the entire group

I am having an issue with Groupy. Most applications behave properly with the exception of Acrobat reader. I typically group together Reader, Outlook, and Chrome. If I close Reader (usual close button or middle mouse button mapped to close), the entire tab group closes and Outlook and Chrome are now hidden (the processes are still alive). If I can actually get them re-appear (e.g. sometimes a click of the task bar works), they are super small and have to be resized. Most of the time I have to kill the entire process tree for Chrome and restore tabs to get back to where I was. 

Reader seems to be the only application that causes this for some reason. Any workarounds besides undocking the tab and closing Reader on its own? Is this a confirmed bug? 

Thanks.

James.