Possible glitch with him, these are my theories on what is going on:
1: A mod is interfering with his Data, causing him to not spawn in the Location.
2: You have a quest active related to him, forcing him to spawn in another location as some sort of Anti-Glitch the develoupers made.
3: You used a command to accidently delete him, causing the glitch.
Fixes: If it is a quest then there is no fix i can think of besides spawning him Via console commands, but that is still unlikely to fix it, Or if you are a Vampire feed on people to LVL 1 then go use a Shrine to be rid of all diseases [MAY NOT WORK FOR DAWNGUARD DLC]