Lord Harkon Disappears

skyrim-dawnguardthe-elder-scrolls-v-skyrim

After arriving at the castle, Lord Harkon gives you the option to become a vampire lord, but when I accept the offer Lord Harkon disappears. The cut scene continues though and I have the power to transform. However, I can't leave the castle without speaking to Lord Harkon. How can I find him or make him reappear?

Best Answer

I discovered the problem was I had already been infected as a vampire and for some reason that was causing problems in the script. Simply taking a potion of cure diseases fixed the problem.