Who Columns not getting updated with the timestamp for table IBY_EXT_PARTY_PMT_MTHDS

For some of the records who columns are not getting updated with the timestamp in the table IBY_EXT_PARTY_PMT_MTHDS.

This is happening mainly for the "ONETIME_PAYMENT"

We are relying on these Who columns to verify the incremental data.

Can you please let us know the reason for these WHO columns not getting updated with the timestamp