As Garin mentioned in this post, one of the new features the team has been working on is Model States.
This might have an effect on some of the Level Of Details related functions, events, and properties in the API.
If you are using any of those, the best thing to do is join the beta program where you can find more details about this functionality and can also use pre-release versions (alphas and betas) of Inventor to test your add-in.
