Steps to reproduce:
1. Open project in "project.zip"
2. Build for iOS
3. Connect a supported MFI controller to an iOS device (tested with Dualshock 4)
3. Deploy the project to the iOS device using Xcode
4. A square will appear in the center of the screen every time you press a button
5. Try pressing some buttons on the connected controller

Expected result: Controller Input will be recognized
Actual result: Input is not recognized

6. Minimize and Maximize the Application

Issue is resolved

Reproducible with: 2017.4.40f1, 2018.4.0f1, 2019.3.0a1, 2020.1.0a16, 2020.2.0a12 (Read notes for reasoning of versions tested)
Could not test with: 2018.4.22f1, 2019.3.14f1, 2020.1 because of 1241180

Reproducible with:
Devices tested:
Reproducible with:
VLNQA00310 iPad Pro 12.9 (iOS 13.4.1)
Not reproducible with:
VLNQA00015, Samsung Galaxy Note8 (SM-N950W), Android 8.0.0, CPU: Snapdragon 835 MSM8998, GPU: Adreno (TM) 540 (XboxOne controller)
AppleTV (tvOS 13.3.1)

Notes:
1. Issue 1241180 (which makes Unity on iOS to not process any Input from controllers) may make this impossible to test in some versions
2. 1241180 is Introduced in 2020.1.0a17 and fixed in 2020.2.0a12, it was backported to 2019.3, 2018.4 streams
3. I tested the first versions of streams 2018.4, 2019.3 to verify that the issue was in these streams, however backports with 1241180 make the issue impossible to test it in later versions of these streams