Sometimes layer is not working properly....

Davinci Reslove can control the contrast regardless a layer.(don't need to care about order of windows or appoint the node)
I think this is one of great benefit of Resolve.
I have two Davinci Resolves and I have a friend who own three Davinci Resolve.
I have used all this five ( Windows, Mac, Hacintosh)
All of these have same problem, that I don't know how to fix and wonder if anyone else has same...

first layer highlight clip with Primary // Second layer bring it down with Primary....

Sometime it does work like 2K plus, and sometime it doesn't work..it just bringdown the clipped highlight.
And I didn't use clip control or clip soft....

Am I doing something wrong?