So i can't keep my thrall's when i turn into a vampire lord?

Have you tried it?

Yes, doesn't work. Was wanting to know if this is a bug because i can keep the gargoyle when i'm human.

Yeah, this is pretty ballsy =/

[censored] it! Might just cure myself of vampirism as it [censored]s me over even more now!

My thralls are only temporally anyway, if Iose one I get another.

I lose them often when raising stronger undead that are unaffected by dead thrall, e.g. draugr deathlords.