Hello Adrian Mace,
If the "world maps" you're referring to is the built-in Windows Maps app on Windows 10, that would explain why the search just grays out. Microsoft retired Windows Maps last year. Search and routing depend on backend services that are no longer served, so airport-code lookups like EGTO and EGMC will gray out as expected behavior of a dead app.
The underlying maps data is still alive on the Bing side though, as Bulldog's screenshot demonstrates, so the simplest path forward is to switch over to Bing Maps:
- Open any browser and go to https://www.bing.com/maps
- Search the airport name or ICAO code directly there
- Optional: in Edge, click ... > Apps > Install this site as an app to pin it to Start/taskbar