Search by email domain returns no results

I need to search my contact list for individuals at a specific company, e.g., @xyz.com. But when I use the search by email domain OR search by Name or Email options, it always returns no results. It doesn't matter which domain I choose or how I do the search. I can search for @xyz.com, xyz.com, @xyz, xyz, and it will always say "no contacts match filter criteria." I can be literally looking at someone's email address in the full list, then do a search for any part of the domain, and it will say nothing is found. Gmail, yahoo, aol, company names, whatever. None of them return any results.