Why am I unable to add a commencing port?

In the below example, the voyage has already commenced. Given the vessel is currently at the loading port it is not possible to add another port before this.

In order to add another port before the loading port in the vessel itinerary, any Port Activities and Activity Reports need to be deleted or the voyage status needs to be changed to "Scheduled“. Changing the voyage status will automatically delete all Port Activities and Activity Reports.