I'm having the same problem. Someone reported the bug on May 8 (NIM-091487), but there is no information regarding when/if it will be fixed.Simple workaround:Include the layer's definition query in the cursor's "where clause" and refer to the layer.dataSource instead of the layer itself when creating the cursor. For example:This doesn't work:MRDroutelogEvents.definitionQuery = "\"TWN_TID\" = '%s'" %twnlr
ghost_query = "\"SR_CATEG\" = 'GHOST'" %twnlr
ghost_points = sorted([item[0] for item in (arcpy.da.SearchCursor(MRDroutelogEvents, ["SR_CATEG"], ghost_query))])
This does work:ghost_query = "\"TWN_TID\" = '%s' AND \"SR_CATEG\" = 'GHOST'" %twnlr
ghost_points = sorted([item[0] for item in (arcpy.da.SearchCursor(MRDroutelogEvents.dataSource, ["SR_CATEG"], ghost_query))]) #(doesn't matter if there is a definition query on MRDroutelogEvents or not)