I had the same issue with trying to package pages in a custom module from the global action. I was able to get it to work using the mass action after multi-selecting the pages I wanted to package and selecting 'Existing Page Pack'
Thank you Craig. This method worked for me as well. I was able to create the page packs successfully this way. Having said that, I did get one error in the console that may / may not shed light on the issue affecting the global action???