I have a solution hosted on FMS14.
I used the FM 15 iOS App SDK with a launcher file to create an app.
The app was approved and is available on the app store. (it requires a password for access)
On my iPhone 6 and iPod everything runs perfectly.
On 2 staff members iPhones (5C & 6S) the Dropdown and PopUp options don't work.
When they press on the field it is selected and if they press again it gives them the option to Paste.
If they wait a few minutes the pop list may appear.
I changed it to a Drop-down list and got the same problem.
All devices are running the latest iOS update (9.3.2. The user had the problem also on 9.3.1.
If they connect via FileMaker Go 14 it works as it should.
To get around this I had to change the Pop-up menu to a popover with a portal to select from.