In ArcGIS Pro, the Shape.STLength() field is removed from the attribute table when a join is applied to a feature class stored in an enterprise geodatabase.

Workaround

• Before applying the join, calculate a new field (such as a calculated length) in ArcGIS Pro using the appropriate geodesic or planar method. This field will persist after the join and can be reliably used in attribute tables and pop-ups.
• If the layer is regularly edited, consider creating an attribute rule (calculation rule) that automatically updates the calculated length field (not the Shape.STLength() field, but a new one of the same data type) whenever the geometry is modified. This ensures the field remains accurate over time without requiring manual recalculation.

Steps to Reproduce