Hi again, I deleted my post that I accidentally posted in the technical issues part of the forum to avoid confusion.
Here is what I observed regarding this bug:
The new (drawing) tattoo system introduced with business and hobbies seems to be very bugged when it comes to occult sim. For example, if the human form of an alien is tattooed and the sim is saved, the tattoo will be gone when the sim is taken from the gallery or moved to a lot (despite showing in the gallery picture). It works if the alien form is tattooed but then the human form is also automatically tattooed. For vampires it similar: if the dark form is tattooed this will not save permanently/correctly and will vanish - so this is again tied to the base form. (I also use no CC, and one alien sim got corrupted in such a way that even the body hair had to be selected for each outfit category separately in human form. When I removed the alien occult completely the sim would be a human sim but alway revert back to its alien appearance when moving to a lot). I experienced a similar situation with mermaids and maybe this applies also to other occults with 2 forms.
In short: it seems that the system might need some more fine tuning with occult sims.