Steps to reproduce:
1) Download attached project and open in Unity
2) Open scene 'ReproScene'
Note: make sure you can see text in the Scene view
3) Select Canvas in the Hierarchy
4) Press Windows key on the keyboard
Text will disappear

Expected result: Text should not disappear after Windows key is pressed
Actual result: Text disappear

Reproduced with:
2018.1.0a4, 2018.1.0a5

Not reproduced with:
2017.2.0p2, 2017.3.0b10, 2018.1.0a1

Workaround: Click on the Text UI element in the Hierarchy and text will appear