Vendor Master changes not showing

Hi,

We are facing an issue with Vendor Master changes. We change the Withholding Tax data but not showing in Account changes --> All fields thru XK03/XK04.

First we delete the Withholding Tax data by Delete Row option....it is showing in change history.

But when we insert another Withholding Tax data, Changed data is not showing....Please see the below screenshot...

Please note 1 thing...that "WH Tax Country" is showing changed history...

What should be the reason???

please guide..