Dimensions missing from Web_Map_as_JSON

[StephenRhea_NV5]

We have a custom print service that we call from a PrintTask. In 3.X, the auto-generated Web_Map_as_JSON parameter included the dimensions of the selected layout template. In 4.X the dimensions are missing (see screenshot below). The height and width properties are populated correctly on the PrintTemplate we pass to the PrintTask, but they don't get added to the Web_Map_as_JSON parameter. What's the correct way to include them?