Hi @RobertChaney
To recalculate the extents in a feature service (published) parcel fabric, the service needs to be stopped and the geoprocessing tool run on the enterprise geodatabase feature classes. The service can then be started and the new extents should be reflected immediately.
This can be done with a short arcpy script:
import arcpy
from arcpy import env
gdb = r"/path/to/enterprise/geodatabase.sde"
env.workspace = gdb
fds = "fabric_feature_dataset"
for fc in arcpy.ListFeatureClasses(feature_dataset=fds):
arcpy.RecalculateFeatureClassExtent_management(fc)
Regarding the "calculating extent" popup, there might be something more going on. I would suggest opening a support case where they can take a look.