cannot save available assignment blocks in displayed assignment block

Dear Experts,

I am trying to add assignment block "Notes" and "Attachments" from

Available AB -> Displayed AB in Trade Promotion Overview Page.

Once I add and do the save, I get a success message also.
But the moment I go out of the config screen and come back I see that the 2 added AB remains in "Available AB" column.

In other words, I am not able to get the new AB to be saved and displayed in my screen.

Anyone faced a similar issue and any idea about the reason and solution (We are using SAP CRM 7.0 EhP1).