Not recognized as vampire

My character seems to reset each time I change to a vampire lord and back again. I am still considered a vampire by everyone in the game except for Lord Harkon and his court. The only physical change that occurs is that my eyes are no longer glowing. I think the problem may be that I am changed to the version of vampirism that came before Dawnguard. How can I fix the problem or keep my character from reverting?