System Attributes ARCS

Hello, I wonder if somebody can help. I am trying to load Account codes under system attributes using the import function. I select the file and set the file delimiter as comma. The Import List Values return the status as Completed Successfully with the number of list values loaded, updated and completed showing the number of records in the file. The value are however not displaying in the list after saving. Tried different file formats but still the account codes in the file are not loaded. This import process has worked before so was wondering if somebody has some suggestions