When all sprites have the same Z value and are in the same sorting layer, later placed sprite disappears and reappears in scene and game view when moving its position in y axis

How to reproduce:
1. Open the attached "2Dtest.zip" project
2. Open test scene
3. Select brown_window_0 and move its y axis
Result: Notice that in 2D mode in Scene view it is always visible, but in game view it is disappearing. In 3D mode it disappears and in scene view

Reproducible: 5.4.4f1, 5.5.0b1, 5.5.0p3, 5.6.0b3

Won't fix: This won't be fixed because we have so many utilities to help order sprites. SortingLayer + order, z-value, SortingGroup, Axis-Distance-Sort. Sprites should always be sorted