Random Number in Material per frame

I need a random number in my materials that change every frame.

To do this I created a Material Parameter Collection that my material uses.

Every Tick, My actor generates a random number and puts it in the property in that MaterialParameterCollection.

Sometimes when I am viewing the Material in the editor it works or savign changes while its running. But other times its as if the value isnt changing. I know the value I am wrtiting to the collection is changing as I am logging it every frame.

To make it harder to debug this is a PostProcess Material I am using that blends with the scene.

Is there a better way to have a random number per frame?
Is there a way to debug these values? (I have used the debug scalar material nodes)
Is there a known reason why it seems to work “sometimes”?