Steps to reproduce:
1. Open attached project "ETC1_Bug.zip"
2. Open "Test" scene
3. Open build settings, switch to Android.

4. Set Texture Compression to Don't Override
5. Click Play Mode in editor
6. Notice that character looks correct.

7. In Build Settings, set texture compression to ETC (default).
8. Click Play Mode in editor.
9. Notice that character transparency looks broken.

Expected behaviour: Textures that have alpha channel displayed properly
Actual behaviour: Alpha channel ignored with ETC1 compression

Reproduced on: 5.2.4f1, 5.3.5p5, 5.3.6p2, 5.4.0f3, 5.4.0p1, 5.5.0a5*.