Is it true that for every LOG_HANDLE in BALDAT you should find a record in BALHDR with this same LOG_HANDLE?
This can arrise for all systems ans can be classed as 'release independent' information.
This situation can occur via wrong custom coding to have deleted BALHDR records without deleting the related BALDAT records.
It can be confirmed that log_handle in BALDAT has the same in BALHDR. Correct or do not use custom coding to delete records in BALDAT and/or BALHDR. Use the SBAL_DELETE program to purge application log data from BALHDR and BALDAT.