Hi,
Please check method IF_FIEB_MAPPING_X~MAPP_BANK_STATEMENT in your system. Described behavior could come from there. In its description your could read:
*----------------------------------------------------------------------------------*
*--- CAMT.054 messages do often have no bank statement number:
* Draw one so that the message are not rejected by the duplicate check
* of the bank statement processing.
*----------------------------------------------------------------------------------*
Put break-point at line
IF <ls_acct_statement>-febko-aznum IS INITIAL.
*--- No bank statement number in the XML in <ElctrncSeqNb>: draw a number
and check what do you have further.
Also you may want to check transformation FIEB_CAMT054_V2_TO_FEB in your system.
Regards,