I am having this issue too but a temporary fix I found on this Reddit thread seemed to help for anyone else dealing with this bug: if you unsave the Sims on Cupid's Corner (as in removing them with the trash can icon after meeting them) and opening the Sim in CAS after unsaving them it seems to fix the vocal bug. I couldn't say what exactly but it does seem to be tied to the Sim being saved to Cupid's Corner specifically.
Thank you so much! Although I already used another method (download the same sim manually from the gallery by checking creator’s name), but it would be useful for people who still have him in the game.
I will try this next time if I use this Cupid feature again.
