Solution : https://service.sap.com/sap/support/notes/1061290 (SAP Service marketplace login required)
Key words : 
cost center - description issues, prerequisites cost center field, account assignment detail, srm [ppoma] f4, backend f4 [be_f4_help, cost center, padded values, terms bbp_pdh_acc, alpha converted, truncate zeroes
Related Notes : 
       
| 1140770 | FAQ: F4-Help Cost Assignment | 
| 982263 | Changes made in account assignment screen 1000 | 
| 935201 | Cost center dropdown not showing all values in acct. ass. | 
| 925890 | Cost centre drop down not working | 
| 892702 | fund center description not retrieved | 
| 871628 | WBS fails to show the description | 
| 545365 | EBP 3.+: Refresh of the attribute texts in BBP_ATTR_VALUE_T |