We are aware that the space bar is not working in auction house searches. And it has been added to the known issues list.
Currently, searches in the auction house are limited to those that do not include a space in the name. A temporary workaround, while we investigate the issue, is to drag the item you want to search for into the “Item Name” field. This will paste the full name, including spaces. Thank you for your patience.
Turbine Community Team