Steps to reproduce:

1. Open attached project (DragTest.zip)
2. Build the 'DragTest' scene for iOS
3. Build and run Xcode project to iOS device
4. When the application is running, touch, drag and release your finger on the image or cube in the scene
5. Look at the Xcode debug log, notice that OnEndDrag and OnPointerUp is not called upon releasing the finger

Workaround: Select 'Main Camera'. In the inspector switch 'Touch Inout Module' with 'Standalone Input Module' by moving one of them up or down. Build and deploy the app. All events are called as expected.

Works as expected in editor.