I discovered in my FM Go (13.0.2 / 13.0.3) solution where Insert from Device (Camera) usually works fine on the iPad and iPhone (iOS 7),
while Insert from Device (Photo Library) or (Music Library), causes the devices to 'freeze' indefinitely with the pinwheel animation,
prior to even presenting a selection dialog.
I was able to get the script step to work in the "Contacts" starter solution (which incidentally, prior to my modification, didn't use Insert from Photo Library).
After eliminating any privilege issues and other conditions, I discovered it was the Freeze Window step that was causing the whole thing to fail.
My routine adds a Contact photo record to a related table, so it starts on the "Contact" screen, freezes the window, goes to the Photos table in a new window, creates a new record,
inserts the photo from the device, and finally closes the new window, returning to the original screen.
Removing only the Freeze Window script step allowed the routine to complete successfully.
Apparently in FileMaker Go the Freeze Window script step behaves differently under certain conditions; such as in this circumstance,
where it's as if the new window does not exist. Yes, I'm aware that FM Go creates "virtual" multiple windows as opposed
to FileMaker Pro's "real" multiple windows.
Again, this worked fine when the source of the Insert from Device script step was "camera," so it was difficult to nail down the problem,
due to 'inconsistent behavior' and lack of any error result which might have indicated to me that the target was unavailable, etc.