Product and version: FileMaker Go 15.02
OS and version: iOS 10
When you have a button on a layout that has a single script step (Note: Not a script - just Action - single step on the button) it doesn't work as expected in iOS10 / FileMaker Go 15.02.
How to replicate:
Create a layout and make a single field called "MyField" and a single button called "MyButton". Under the Action dropdown for the button choose "single step" and set that step to be "Insert from Device [MyField; Type: Camera; Camera: Back; Resolution Full]. When you click on the button on the iPad it will not work. (In my environment the iPad is connected to a file hosted on the server - not sure whether or not it makes a difference for this issue)
If you change the button to instead "Perform Script" and make it a one line script rather than a single step action for the button then it works as expected. Also, if you use the earlier version (FileMaker Go 15 with iOS 9) then it also works as expected regardless of whether it is a script or a single step attached to the button, so this is very environment and version specific.