Not sure why this statement wouldn't run within an edit session in arcpy:
edit = arcpy.da.Editor(gdb)
arcpy.CalculateField_management ('Export_Output', 'Point_Type', 'UNKNOWN')
I am working with a versioned replica in SQL Express. Working on the default version.
Solution: I just ended up using da.UpdateCursor to calculate all recs to 'UNKNOWN'. This worked fine. Was getting strange results otherwise (on small and large datasets).