Supplier Site-Level Bank Account End Date not sticking (even after Save is confirmed)

We have set the End Date on some Supplier Site-Level Bank Accounts and then we Save. We receive the confirmation at the top of the screen that says "The changes to the Banking Details have been saved". However if we go out and back into the screen again, the End Date is cleared / has disappeared / is not sticking. What could be causing this? This issue has been seen for multiple different users for multiple different suppliers. Are there any type of validations that run behind the scenes where you are not allowed to end date a supplier site