You need to set some of the overrides in the FPostProcessSettings
struct too. It works similarly to when editing the values in engine with the checkboxes.
Try:
void FunctionBeingTicked
{
FPostProcessSettings PostPro;
PostPro.bOverride_ColorSaturation = true;
PostPro.ColorSaturation.Y = NewValue;
PostPro.ColorSaturation.Z = NewValue;
PostPro.ColorSaturation.X = NewValue;
VRReplicatedCamera->PostProcessSettings = PostPro;
}
This is actually mentioned in the header file for CameraComponent:
/** Post process settings to use for this camera. Don't forget to check the properties you want to override */
UPROPERTY(Interp, BlueprintReadWrite, Category = PostProcess)
struct FPostProcessSettings PostProcessSettings;