I first noticed this on desktop, then tried it on mobile and did not experience the same issue. However, on subsequent attempts on mobile, I did start experiencing the issue. Search sometimes requires you to add a trailing slash when you begin adding words to it in order to have it refresh the results, which is confusing as at first it seems like your search did not work.

Here's an example video I took on mobile showing it working correctly: Video link

And the desktop video showing the trailing slash bug: Video link

I'm attaching screenshots of when I experienced the bug on mobile in another attempt. I also sporadically get a random set of search results unrelated to the first word and that don't appear on desktop (and vice versa with desktop on mobile). I'm not really sure what causes this.

Steps to recreate
So we're trying to find Victim by Andrew Boryga.

1. Go to the website. Type in 'victim'. You should see several results pop up, though this one isn't in them (understandable - I know there's the trying to find balance between exact match and what people are actually looking for).
2. Then, add a space and the author's first name - 'victim andrew'. At this point, it should pop up as the top result; however, this does not happen. The results do refresh, but our book is not in them.
3. Add a trailing space - 'victim andrew ', at which point the results will refresh again and you'll see the book you're looking for.