I think this is a bug and not something I've done wrong. I use the bookmark search extensively throughout the day and know it was working until recently. But now, searching for Safari bookmarks using a keyword offers me no results. I get the "Search bookmarks" prompt, but there are no results, whatever I type in.
I think this coincided with the most recent update of Alfred, but can't be certain when it started. Chrome bookmark search works fine when I try it out.
Alfred 4.6.2, MacOS 12.2, M1 MBA
Cheers