To reproduce:

1. Download attached "TextureIssueTest Project.zip" project and open in Unity
2. Open "TextureIssueTest" scene
3. Enter to Play mode

Expected results: All Sprites in Game window are rendered correctly and without any graphical artifacts
Actual results: Some Sprites in Game window are rendered with graphical artifacts

Notes:
- This issue is reproducible only on macOS
- If you reimport all Sprites, this issue disappears bu once you restart the Unity Editor, the issue comes back
- Image for Reference is attached in Comments section
- Workaround: Disable Metal Editor Support in Player Settings

Reproduced on Unity 2017.4.0f1, 2017.4.32f1, 2018.4.10f1 and 2019.1.0b1