problem with mip maps level 0 miss on android

Unity Engine
1

Our game have a problem on some Android machine, the setp is:
1.run game.
2.when loading new scene ,press home key ,After minimizing the game and resuming,the texture mips level 0 be miss,I use Adreno Profiler tool see that is black.

but ,if i turn off mips on texture Import setting,it is fine。my shader is very simple, use unlit sahder。

unity3d ver: 4.6.4f1
ANDROID: 4.4.4;
GPU :Adreno405;
CPU:MSM8939;
2GB MEM;
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2

I have tried to change the Settings(use 32bit display buffer, 24bit depth buffer, stitic /Dynamic batch,multithreaded rendering …etc),
but the problem still happen!

3

I’m not very knowledgeable in this realm.
What happens when the mip level is lowered? 10 seems to be overkill imo. Couldn’t 4 mip levels be enough?
Is there actual benefit to having mip levels below 64x64 on an entire character sheet?

4

The Max mip levels is automatic generation,I can’t control.