Thanks @ben and @digitalchild
I have done some more testing…
It appears that when a vendor modifies their Store title – it changes it in the backend and the Vendor Store is now named what the vendor called it however the permalink in the vendor dashboard for “View Store” still shows the old store name in the URL however of course it doesn’t lead to their store, you have to manually change the URL to be the new store name and then it works.
Ta!