Funnily enough, Google Maps resolves the same text query to a different place and seems to be confused by it as well, even though this map marker shows the address formatted pretty much the same. In any case, it would be cool if searching for SU46, The Grand Arcade, St Andrew's St, Cambridge CB2 3BJ worked on openstreetmap.
I’m not sure, the maximum zoom level seems to be too small for me to tell. It could be that there’s no such marker at the location. I assumed the store would be relatively famous though, so it would surprise me if it wasn’t mapped.
The extra bits like SU in SU46 and The in The Grand Arcade, plus including St Andrew’s St, would be what’s making it hard for Nominatim to find it, since you’re adding extra details that don’t line up with what’s mapped, which means we’d expect the search to potentially not work.
Also, searching for Raspberry Pi alone works perfectly.
I’m not entirely sure if the unit number also doubles as a ‘house number’ in that shopping mall. If yes, it should be re-added again (without the SU prefix).
For example, the boutique next door lists its address as:
St Andrews Street
21-22 Grand Arcade
CB2 3BJ Cambridge
We can’t use it as a source, but also we can’t trust it. I don’t see “The Grand Arcade” referenced anywhere else, the website says “Grand Arcade, St Andrew’s St, Cambridge CB2 3BJ”.
The Grand Arcade website says “SU46, St Andrew’s Street, Cambridge CB2 3BJ”. I wonder if “SU” stands for “Store Unit”, if so it sounds like addr:unit to me.