Im having trouble labeling a line feature with its Shape.STLength() field info.

Apparently, Essentials (Geocortex in general...?) doesn't like labeling features based on this field. I have created a 'dummy' field with the same data type, same numerical data, etc.) and the labels come across just fine in my final Essentials Site. Perhaps SQL geometry-enabled fields are not available for labeling in Essentials (...?)?

If so, why? If these fields are available for labeling, is there a method Im not familiar with?