Reproduction steps (Reproduction video attached):
1. Open the attached project.
2. Build it to iPad.
3. Make sure at least one other application is running in the background (Tested with 'Settings').
4 Run the Unity application.
5. Click the 'Button'.
6. Swipe to another application using 4 finger motion.
7. Swipe back,
8. Wait for 1-5 seconds.
- Video will freeze.
9. If the video will not freeze, repeat steps 6-8 up to 5 times using different time intervals between swipes.

Notes:
- Reproduced with any combination of 'Settings > General > Multitasking' settings.
- Final Xcode lines:
-> applicationWillResignActive()
-> applicationDidEnterBackground()
-> applicationWillEnterForeground()
-> applicationDidBecomeActive()

Reproduced with:
5.6.0f3, 2017.3.0b5
Pad Mini 3 iOS 10.3.2 (000016)

Could not reproduce with:
iPad Air 2 9.2
iPad 5 10.3.3
iPad Mini 4 11.0
iPad Pro 10.5" 11.0
iPad Pro 10.5" 10.3.3