When setting up global parameters, if you set them up with default values and do not change those values, any uses of that global parameter will output nothing.
If you then change the value, the parameters are generated everywhere they are used.
E.g. set up global parameters as follows:
{
"layout-width" : "size|50%"
}
If you then apply {{dc:p:layout-width}} to a div for example, the width will be set to nothing:
div {
width: ;
}
This applies to the Page / Global CSS, element properties such as width, and also the content of the elements themselves.
As soon as a value is logged, it will render and display correctly.
The expected behaviour is as it happens for the element / component parameters, where the default value is rendered if no value is entered.