The issue is simple, I have a layer in a map document (main_layer) and a (source_layer). I want to apply the symbology from source_layer to main_layer and then change the classBreakValues attribute. My python script is simple
source_layer = arcpy.mapping.Layer(symbology_layer)
break_values = [1., 2., 3. ,4.]
arcpy.mapping.ListLayers(mxd).symbology.classBreakValues = break_values
arcpy.mapping.UpdateLayer(df, arcpy.mapping.ListLayers(mxd), source_layer, True)
However, in the source layer, the outline has width 0 but **only when I change the break values**, the width reverts back to default.
I have updated to Arc 10.2 and this is still occurring.
Also, the reason that I change the break values before calling the UpdateLayer function is because when I do it after, I get:
File "C:\Program Files (x86)\ArcGIS\Desktop10.2\arcpy\arcpy\arcobjects\_base.py", line 89, in _set
return setattr(self._arc_object, attr_name, cval(val))
which I think is also related to this (unanswered) question.
Thanks to anyone that might be able to help. I would be happy to share mapdocuments and code for replication.