I recently installed the addon so I'm not really sure this is an issue. Can you please take a look at screenshot attached below. Why is [Breath of Mastery] listed as unknown when I have it learned and addon also says that "This was never available to players.
I also tried refreshing data but didn't helped.
Thank you.

they are different spellIDs. if you turn on "collected things," you'll see that the implemented version of this enchant is also included in the book:

if you go to the 'unobtainables' tab in the options, you can scroll down and check 'Never Available' in the 'No Chance' section and that listing should disappear.