"Metal: Cannot read pixels from restricted buffer. Uncheck 'Metal Restricted backbuffer Use' in PlayerSettings." when setting is already unchecked

1. Start a new project
2. Edit > Project Settings > Player
3. Ensure that "Metal Editor Support" is checked, and "Metal Restricted Backbuffer" is unchecked
4. At the empty scene, toggle on "2D" (skip this step if you started the new project in 2D mode)
5. Play and exit Play, three times
6. After exiting, click anywhere on the empty scene

Expected: No warning
Observed: "Metal: Cannot read pixels from restricted buffer. Uncheck 'Metal Restricted backbuffer Use' in PlayerSettings."

The warning tells the user to uncheck 'Metal Restricted Backbuffer', which is already unchecked.

Occurring on: 2017.2.0b1 (first appearance of this setting) onwards till 2017.3.0a1 (current latest trunk)