Just to answer your questions, yes there are keys defined and these are regular tables, not views.
Having said that, as of today I am now able to see and work with the geometry in Map 2013. It looks as though it might have been a DB permissions issue afterall. I thought that the user credentials I was logging in with were set up as data owner, but I had our IT dept. help out with some related data access problems, and in the end this user id was set up in SQL Server as sysadmin. I didn't have a chance to test this on Friday when he made the change, but it is certainly working today, so I have little doubt that this was the fix.
I appreciate your time spent with me on this, and I feel a bit sheepish about not paying more attention to the db roles thread you linked me to in your earlier post. Anyway, yay, it's working!
Thanks for the reply. I'm glad that you narrowed it down and nailed the issue! Thank you for the details which will help anyone else who experiences a similar issue.