Just found this wonderous universe today and tried to install the app on my devices with no luck. I have an iPhone 5, iPad Air, and iPad Mini all on 7.0.4. They are all jailbroken and I have installed AppSync for 7.x.x from Cydia.
Everytime I download the AppSync application from app.appaddict.org through safari it downloads, then tries to install. It goes fully around the circle to install, but then goes gray again and a few seconds later attemps to install again.
Tried installing on all three devices and get the same result on all three.
Thanks for any advice/help in advance!
Update: Looks like Winterboard is the conflict. Issue resolved.