If you're in a situation where you can't update a due date because of date/time release conditions, you can perform the following:
- Remove the release conditions on the item that needs a new due date. You can set the item to "Hidden from students" and this will remove/strip all date/time release conditions.
- After the release conditions are removed, change the due date.
- After the due date is changed, apply your desired release conditions or set the item to "visible to students".