What's up with the T460x Thinkpads and Ubuntu?

Why are they not officially certified for Ubuntu? Is there any particular reason?

I have read in some threads that there are problems running Ubuntu on them. Some things don't work and there are bugs. I am planning to buy one, but I want to run Ubuntu without much problems and now I am wondering: will those problems be certainly fixed in the future and do they only exist because these Thinkpads are so new?

For example the fingerprint sensor doesn't seem to work on Ubuntu.