When a linked account/consolidated account that has previously been used as a designated payer account moves under another billing block, you will find that Savings Plan - Unused ceases burning down. It will remain under the previous designated payer account in cost reporting while continuing to burn down/display under the new designated payer it sits under.
To workaround the Savings Plan - Unused cost under the original designated payer account, you can make use of a Custom Line Item Rule, to provide a credit that matches the Savings Plan - Unused cost following the day of the account move.