Hi Mike
I'm searching on Ancestry.com and Ancestry.co.uk with exactly the same criteria, i.e. either just name, or name and county where the person is living and in particular I used the spelling that I know is on the census that I know are on Ancestry.
With Ancestry.com, the searches show up, but on Ancestry.co.uk, just the message about no search results.
I'm giving up on this now, because until my sub expires, if I want to use Ancestry, I'll go via the American site. Most times I only use Findmypast as I like that site much more.
Lizzie