Thank you for you help everybody. I tried a few things like rebooting but ultimately this turned out to be an issue with the site I was searching. I set up a couple of other searches on other sites that worked fine (after some tweaking) so figured it must be a site issue. After that it all fell into place.
For more detail, instead of relying on opera to set up the search I performed a search on the site then used the results in the address bar to inform what text was used for the search replacing %s with the search term. With the Magic site it was a little more complex. The basic search didn't work at all but using an advanced search narrowed down to the name of the card I got a result I could use to make the search. Hopefully that info helps someone else struggling with the same/similar issues.