I just thought I would detail what worked for me.
1. converted my mp3 to m4a then renamed to m4r (lots of how to on web for this)
2. in itunes via the preferences - general - make sure tones is checked.
3. select tones from the top left drop down list in itunes.
4. assuming my ringtone.m4r is on my desktop - i double clicked it - then it showed up in tones pane. Import to library DID NOT do it.
5. Sync as normal to the iphone.
5a - you may need to enable sync of tones if asked.
6. ringtone showed as expected and i could select it.
sweet jesus it worked
thank you