Hi,
do you have Note 1507027 Description of generic account assignment clears on refresh implemented in your system?
The description for the accounting fields comming from FM - BBP_PDH_ACC_GET_DESCRIPTION and assigned to the accounting data in
Class: /SAPSRM/CL_PDO_DO_ACCT_ASSGMNT
Method: /SAPSRM/IF_PDO_DO_ACCT_ASSGMNT~GET_ACCOUNT_ASSIGNMENT_EXTRA.