Time.timeScale does not work on ios 8.3 build by Unity5.4.1f1

I use the Unity 5.4.1f1 and 5.5.0f3 to build a project for ios. In the project I use the Time.timeScale for control the game, but it does not work on the ios 8.3. The Xcode version is 8.2.1. The Unity version is 5.4.1f1 and 5.5.0f3.

Whatever I use Time.timeScale = 2.0f or Time.timeScale = 0.5f, I show the log , the Time.timeScale is always 1.0;

But I run the same game on ios 10.1 or ios 10.2 ,the Time.timeScale worked perfect.

Does anyone has the same problem, help me . Thanks a lot！