If an iOS device is set for use with Unity Remote in Edit > Project Settings > Editor, if a key is held down during play mode, it will get reset to its 'up' state in a few seconds even when not using the Unity Remote app.

Steps to reproduce:
1) Open the attached project.
2) Plug in an iOS device into the computer.
3) Go to Edit > Project Settings > Editor and select the device to use for Unity Remote.
4) Press play.
5) Press and hold down the left mouse button in the Game view.

The state of mouse input is logged in the console. At first, the input is registered normally, but after a few seconds it is reset even though the button is held all the time. This does not occur if 'Any Android device' is selected, or when no device is set (None). This happens with any key input (mouse buttons, spacebar etc.). After releasing the button, its input is sometimes not registered at all afterwards.

Note: the issue does not reproduce if Unity Remote is running on the connected iOS device.

Reproduced on:
5.5.0b4, 5.4.1p1

Did not reproduce:
5.3.6p5, 5.2.4f1