Phrase searching on a mobile device is flaky and often doesn't return results for text that I know exists. For example, yesterday I wanted to look up a hymn, so I ran this search:

It sat then spinning for several seconds, and returned no results.
Then I immediately retried the search, and got the hits I expected:

I used to think it was overloaded servers on Sunday, since that's when I use the mobile search the most. But just now (on Monday evening) I was able to duplicate the failure using the same search phrase. It seems to be limited to phrase searching with quotes, probably because that's the slowest kind of search.
I hope this can be fixed, as this has been occurring for months and is rather annoying. At least return an error message instead of "No results", because it's misleading.