Moving a WO to alternate resource on Production Scheduling error

Summary:

Hello,

We are trying to move a WO from primary resource to alternate resource on the gantt chart. This has always worked before. But today we see an error as below:
Close Offloading isn't allowed for operation UAT1765 MEA-0625, or the operation has already been transacted.

The WO is a new work order and is not closed. Can any expert help on this?

Content (please ensure you mask any confidential information):

Hello,

We are trying to move a WO from primary resource to alternate resource on the gantt chart. This has always worked before. But today we see an error as below:Close Offloading isn't allowed for operation UAT1765 MEA-0625, or the operation has already been transacted.