I’ve already mentioned this strange behavior.
Actually, there are two ways to add a Fixed lease:
Either from a dynamic lease assigned using the “Add” button,
Or directly in the form and click the “Add” button.
In both cases, the page refreshes to allow you to modify the record (especially the address when adding from the list of dynamic leases) using the “Update” button.
The record is added (or modified) in all cases.
But you have to click on “Update” to enter the next record
Just something to be aware of.