Touchscreen keyboard changes value TouchScreenKeyboard.visible to false when typing to input field. Keyboard stays active, but can't input any text. It happens for no reason, without pressing Return key or pressing out of keyboard area. Only reproducible when tapping on input field a few times before making any input to input field.

Repro steps:
1. open repro project "KeyboardAutoHiding.zip".
2. build to WSA 8.1 platform.
3. deploy on tablet.
4. Tap a few times on input field, so touch screen keyboard could show up a few times. Now start typing text on keyboard. While typing text, input field loses focus, but touchscreen keyboard stays active. No input can be made.

Reproducible on 5.3.4, 5.3.5 versions.
Not reproducible on 5.4.0f1.

Workaround: Don't tap input field multiple times before entering any input.