Can't change URL of a site in the Identity Safe Vault

One of the sites I visit weekly has just been revamped and the URL of their log-in page has changed. As a result, my Vault's auto-fill is rejected. I edited the site to change the URL but get this message:

Norton Identity Safe cant change Mail URL 2017-07 18th.PNGObviously I don't want to change MY details so is there a workaround? Or will I have to remove the existing details and start again by visiting the new log-in page?