Reproduction steps:
1. Open the attached project.
2. Select 'Ocean_Reflection Probe 4-reflection_mobile' in the project tab.
3. Make sure iOS or Android platform icon is selected in the Inspector.
4. Make sure "RGB Compressed PVRTC 4 bits" Format is selected in the Inspector.
5. Click 'Apply' if 'Apply' button is not gray.

Actual behavior:
- "Forcing RGB 24 bit format because the compressed size is larger than uncompressed"

Notes:
- "RGB Compressed PVRTC 2 bits" works as expected.
- Case 863225 may be related (It fixes the warning, but doesn't fix the actual issue).

Reproduced with:
- 5.3.8p2, 5.4.6f3, 5.5.6f1, 5.6.6f2, 2017.1.4p1, 2017.2.3p1, 2017.3.2f1, 2017.4.5f1, 2018.1.5f1, 2018.2.0b8, 2018.3.0a1
- iOS, Android

Not reproducible with:
- 5.2.5f1