Spotify search on my iPhone is showing incomplete / missing results for songs. For example, it will not find any song with the name "Darkhaast", though the song is in various albums when I search on my computer in the Web player. Similarly, all songs from the album " Best of Sunidhi Chauhan" (https://open.spotify.com/album/0C0uXvpwQG1dRuHGLSvBTT) do not show up in search results on the iOS app. This is with Spotify fully online; I am not searching for offline / downloaded songs.
There is no issue with search with Spotify on the web. So it appears to be an iOS app specific issue.
Hopefully this bumps the topic, but I have had the same thing happen. Tried to search for Nobody by Eliza Doolittle and it would not come up no matter how far down the list I checked, searching for her by artist I found it in one of her albums, so why didn’t the search function see it? I even typed “by Eliza Doolittle” after it which seems to work with other songs.