Solution : https://service.sap.com/sap/support/notes/562169 (SAP Service marketplace login required)
Summary : 
      SAP Note details a truncation issue in line item reports concerning auxiliary account assignments fields such as OBJNR_N1, OBJNR_N2, and OBJNR_N3 where WBS elements cannot be fully displayed due to a character limit (18 or 22 characters). The truncation stems from initial use of an internal format adequate for fewer characters, now deemed insufficient due to a switch to the external format. Solutions include enhancing reports with user-defined fields matching desired lengths, adjusting program SAPLKAEP, and implementing corrections through customer exit '001'.
Key words : 
work breakdown structure element, line item reports, auxiliary account assignments, terms key words, line item report, user-defined field, desired field length, respective wbs elements, field extensionprograms, respective object
Related Notes : 
       
| 896531 | CO-EP reports: Customer-specific authorization checks | 
| 591963 | Co EP-reports: Restriction on characteristic BELKZ | 
| 353639 | CO line item reports: Display auxiliary account assignment | 
| 325546 | CO line item reports: Creating a user-defined field |