Reproduction steps:

1. Open "Editor_Inspector_Bug.zip" project
2. Open "Main" scene
3. Select the "Red Object" in the Hierarchy window and set it's "My Vector 3 (Script)" "My Vector" Values to '1'
4. Do the same to the "Blue Object", but set the values to '0'
5. Select Both of the objects in the Hierarchy window
6. Click on the "ZERO" button in the "My Vector 3 (script)" script
7. See that the values are set to '0'
8. Select the "Red Object" in the Hierarchy window and set it's "My Vector 3 (Script)" "My Vector" Values to '0'
9. Do the same to the "Blue Object", but set the values to '1'
10. Select Both of the objects in the Hierarchy window
11. Click on the "ZERO" button in the "My Vector 3 (script)" script
12. See that that doesn't set the values to '0'

Expected Result: All configurations should set the Vector3 values to '0'
Actual Result: Only some of the configurations set the Vector3 values to '0'

Reproduced with: 2018.3.0a1 (c7051b), 2018.2.0b5, 2018.1.2f1, 2017.4.4f1, 2017.3.2f1, 2017.2.3f1, 2017.1.4f1

Note:
Sometimes this error appears:
"SortIDsInVisiblityOrder failed: n != n - 1"