Updating closed segments
It is not possible to modify some attributes of a closed segment.
The logical workaround (removing the closure and closing again after the update) will frequently fail, read next section.
Closing recently created/updated segments
It is not possible to close a recently created segment, until the segment is fully created by a map update.
Some recent changes do not allow closing a segment, or closing one direction of a segment, until the change is fully applied by a map update. In such a case, it is sometimes possible to create "short term" closures, expiring within the next 48 hours. As an example, after changing a two ways street into a one way street, it is possible to immediately close the forbidden direction, if the closure expires within the next 48 hours. Such “short term” closures can be extended later if necessary, if the end time remains within the next 48 hours.
It is not possible to close a deleted segment: it is not possible to apply closures from the "Current live map" view of the WME.