Chad Callihan resolves an issue:
I connected to the latest SQL Server, opened SSMS, and tried to restore from there. Sure enough, I was presented with the error:
Cannot access the specified path or file on the server. Verify that you have the necessary security privileges and that the path or file exists.
If you know that the service account can access a specific file, type in the full path for the file in the File Name control in the Locate dialog box.
Read on for the solution, which was easy enough, but serves as a reminder that having (and occasionally running!) idempotent configuration scripts can be quite useful.