Clearing the Stated Area in the Parcel Details dialog box so that the value is recalculated based on COGO values fails to include metric units of measure.
Duplicate of BUG-000102741: Also, the best practice and intention of the stated area is that it should reflect the value recorded in the deed or plat. It is a user editable field and can and should be modified to reflect the value recorded on the deed. http://desktop.arcgis.com/en/arcmap/10.3/manage-data/editing-parcels/the-parcel-fabric-layer.htm
解决办法
Run the Field Calculator to manually append the desired metric unit of measure.