Text field disappears after refocus because of .dll and .mdb files conflict

Reproduction steps:
1. Open the attached project "case_840970-Unity";
2. Open Main Scene;
3. Go on the Game window;
4. Minimize Unity program;
5. Maximize Unity program;
6. Change Text Field parameters or pull Game window;
7. Repeat steps with the attached project "New_Project_840970".

Actual result: The text disappears after refocus and shows up when you active window (example: change Game window size) or change Text field parameters.
Expected result: The text always is in display.

Workaround: In Demigiant folder (which is in the Assets window) are stored DOTween files, the conflict is between .dll and dll.mdb files. When they are placed together, the text disappears from the scene. But if you delete one of them: .dll or .dll.mdb files, everything works properly. Also, when I created new empty project with Text field (Unity 5.5.0b3), everything works properly too.
dll.mdb files are created with the pdb2mdb converter (using Unity's UnityVS MDB generator). So this converter creates the dll.mdb files which are causing the conflict with dll files. Because of this a bug with the Text field appears in Unity.

Reproduced with: 5.2.3f1, 5.3.0f4, 5.4.0b15, 5.5.0a6, 5.5.0b2, 5.5.0b3, 5.5.0b8, 5.6.0a1.