Incomplete folder info in Mac mail from Yahoo

Running on a Retina 5K, Yosemite OS.

I have a Yahoo account that mostly works in the integration with Apple Mail. What works is getting emails, sending emails, moving emails between the Yahoo folders. What doesn't work, and this is fairly recent, is that when I created a new folder in my Yahoo mail, it is not made visible on my Mac. All my older folders are there and work just fine, but it's the newly created folders which don't seem to sync.

However, on my iPhone and iPad, I can see the newly created folders in the Apple mail.

I ran the mail troubleshooter and it passed on all accounts.

Do I need to delete and reinstate my Yahoo account on the Mac? Is there another fix?

thanks.