Reasons I think Anos might have Immunity to Mind Manipulation, possibly even Soul Manipulation:
1. Memories =/= Mind and thoughts. Anos can keep his memories at his source, so affecting his mind =/= affecting his memories at his source.
2. The source is deeper than the body, soul and mind, so if Anos can cast magic with ONLY his source, then it obviously means he doesn't need his mind to cast magic.
3. In his fight with Ivis, he was killed by having his time accelerated infinitely. Basically, his body aged an eternity. Anos only has longevity, and he himself stated he can't live an eternity, so unless the soul and mind can remain intact after literally ageing past their limit, it's safe to say that Anos regened his body from ONLY his source. He himself also stated that he can use magic from ONLY his source.
4. In his fight with Wesnera, Anos was incapped. He was actively affected by paralysis inducement, power nullification, perception manipulation and mind manipulation. Despite this, Anos was still able to act as only a source.
So, Anos can either "think" with his source or his source can act on its own. Either way, I believe this can grant him immunity.