Reproduction steps:
1. Open the attached project
2. Open scene "Test"
3. Enter Play mode
4. Click on the sprite in the center in the game view
5. Notice console output
6. Select GameObject "Unit" in the Hierarchy and change Z position (doesn't matter to what) and then change it back to 0
7. Now click on the sprite in the center again
8. Notice console output again

Actual behavior: Sprite is ignored by a raycast even though its order in layer is higher.
Expected behavior: Raycast should respect order of layers.

Note: This case had similar issue but it's not exactly the same, the issue in that case is still fixed (not regression).

Workaround: changing object "Unit" Z coordinate and then reset it back to 0 fixes the problem.

reproduced on: 5.4.0b8, 5.3.3p2, 5.2.4f1