Post process in thirdpersoncharacter BP doesnt work

Hi guys.
So today i tried to make a postprocess effect in my thirdpersoncharacter BP but i cant get it to work with unreal engine version 4.12.5.

I tried to do it with version 4.8.3 and it works just fine.

So what I did tried was:

In thirdpersoncharacter Blueprint, event graph; R (Button) → flip/flop → then postprocess effect; enabled true and false

It works fine with unreal engine 4.8.3 but it wont work with 4.12.5 please help me guys