It seems the way reality works to hide and mask vampires is not an active magic used by them, but a function of the surrounding reality.
A vampire once somewhat more powerful, will reach a tipping point when their magic is "active", after passing a period of spiritual struggle or torment. This may or may not be the period of insanity some experience.
A force of nature is an immobile, immortal object in the minds of all beings living within its sphere of influence. Like a large boulder on everyone's path, they have to cope with its existence, it cannot be ignored. This makes everyone upset when a new force is in formation, because it places a restraint where non existed before.
After all spirits, whether incarnated or not, have worn themselves out trying to maintain their old habits, they will come to accept this new immortal object. They will no longer attack it, but they retain their previous attitude. For those who claimed omnipotence, they will simply pretend that the vampire doesn't exist, because if they admitted to its existence, it would expose a weakness within them.
This causes beings to come up with elaborate and creative ways to keep the vampire hidden and its influence behind a smoke screen. They will even bend time and space to make matters play out in ways that does not expose the thing they have submitted to.
All the while they are also forced to support the vampire, keeping this indestructible object happy so it doesn't come forward, as this would destroy the image of themselves these beings have created.
