I am not able to sort data line no wise its giving error.

On the PO tax screen, when going into the additional tax screen, the line column not in sorted form. Please help as users are facing a lot of issues when working on more than 20 lines, it's very hard to find line numbers as these are not sorted. When trying to sort it's giving the following error:

"The table cannot be sorted because it has pending changes which would be lost"