Picking another site on an existing work order kept the old site's POC
name, phone and notes in the fields. When the new site's record failed
to load, the dialog never synced it, Save stayed enabled, and the work
order pointing at the new site was saved with the previous site's
contact and notes as its override.
A site switch now empties the POC name and phone for every work order,
and the notes for existing ones, so the fields hold either the new
site's record or what the dispatcher types for it.