May I ask you how you are trying to do this and what version of iTunes is current on your Mac.
I mean no offence here, it's just that some things have changed with each version of iTunes and this often includes the way you achieve things like Genius.
The latest iTunes is 12.6.1.25.
The way to make a Genius Playlist with this version, anyway, is:
choose a song; Right Click on it; dropdown menu gives you lots of options including Genius > "Start Genius" and "Save as Playlist".
"Start Genius" selects songs based on the chosen one and plays them till you stop it; whereas "Save as Playlist" does just that and you can choose how many songs you want in the list etc.
Please post back with your version of iTunes and maybe your present Operating System.
Not to be a nitpicker Ian, but I just thought I'd mention, especially for anyone having problems with iTunes v. 12.6.1, Apple released a later build version:
The new iTunes 12.6.1 update does have a slightly higher build number at 12.6.1.27 compared to 12.6.1.25 on the previous release, although any changes are likely very minor considering the version number going unchanged. https://9to5mac.com/2017/05/23/itunes-12-6-1-2/
Yes, I had problems with my iTunes 12.6.1 update crashing on opening, but got it fixed prior to the later build release. Not too impressed Apple and doing so was a big time waster.
I have the latest version of iTunes and have manually updated genius several times.
My library is up to date and tidy. Any imports I make to iTunes, I always make sure to match with the information on iTunes Store. It is as if Genius was shut off from adding new release music to the Genius database in late 2015 or 2016. Music that is released till around fall 2015 works fine for the most part.
I'm about the last or worst person to post about iTunes and its quirks, (I almost hate the multi-purpose confusing app) but what about creating a new Genius Playlist and deleting any old one. Sort of like trashing a goofy or corrupt preference/plist??? Just a hunch here.
But Apple does say: If a song has no Genius suggestions
Your Genius results are automatically updated once a week when iTunes is open. You can update them manually—for example, when you add new music to your library from a CD or a website.
Choose File > Library > Update Genius.
To create Genius playlists, Genius Shuffle, and Genius Mixes, iTunes uses anonymous information about your library and other iTunes libraries. The iTunes Store updates its Genius data constantly, based on new information from the iTunes Store and customers’ libraries. https://support.apple.com/kb/PH19488?locale=en_US
Maybe things aren't getting updated for you properly???
Or could you have something blocking any update???
Not to be a nitpicker Ian, but I just thought I'd mention, especially for anyone having problems with iTunes v. 12.6.1, Apple released a later build version:
Patrick, you're not nitpicking at all. I'm most grateful to you and for your linked article to 9to5mac.
What is interesting is that iTunes > check for updates and the App Store on both my iMacs (Sierra) show version 12.6.1.25 as the latest version - but that is wrong, it should be .27 as you said. Your 9to5mac article mentions several people in the same position as me. No update available.
Maybe it is still to come. Occasionally updates are staggered and, for all I know, the .27 version may be country specific.
Whatever, your post has got me interested and I'll research this. Thank you again.
But don't quote me that it's actually the iTunes 12.6.1.27 version.
Neither does my Mavericks Software Update list any iTunes update that I'm currently using, and I'm not sure what my Sierra has installed or available, but I think it's also the 12.6.1.25 build version.
EDIT:
I just checked my Sierra volume and Get Info says it iTunes v. 12.5.4, so I guess I have some updates to install when I boot Sierra next time. Not sure when that will be as it really doesn't impress me, and it seems slow and it's on the most outer partition of my 1TB HDD.
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