You've got ****loads of stock that isn't moving. You can fix it, by simply making an Errata document. You know all those YouTubers you gave review copies of the Codex to, those same YouTubers who couldn't really talk about the Codex without saying a ton of negative comments and thus, losing their access to GW? Yeah. Them. Ask them what's wrong with the Codex, ask them how to fix it. People aren't stupid, they're willing to try and fix your game.
As I recall, GW released an errata for the wolves straight after release and everyone flipped their ****.