Sometimes black or magenta (pink) textures after loading game on Android

Hi,

I am having some weird visual errors when loading and running the game on android devices. Sometimes when the game loads it shows magenta (pink) textures. This problem is 100% repro by the following steps. (tested on Samsung Galaxy S7 and S8, Sony Xpedia Z3, and Nexus 5X)

1. Launch the game

2. As soon as it starts loading, press the Android home button before splash screen appears.

3. then, get back to the game (resume the app).

Result: Magenta textures and weird visual problems.

I am using Unity 5.6.0f3, the game has only one atlas 2048x2048 and the rest are small images used for UI elements and profile pictures. I am not using any fancy shaders, just the ones provided in Mobile.

Any ideas? how can I work around this issue? thanks a lot.