I'm currently completing the post Elite Four content where you find all of the Ultra Beasts.
I've already found and caught the first three, but I'm having trouble finding the fourth one, Kartana. I have been searching all over Route 17 for over an hour, but it has not appeared.
I know I have already talked to Looker for sure because I remember that Looker's partner felt pain after the appearance of this Ultra Beast. Nanu then gave us advice on where to find it.
So why am I having issues finding it? Any suggestions?