So, I've apparently figured out the problem.
Here's what I need to do:
1. press ctrl + shift + c
2. type testingscheats on
3. type cas.fulleditmode (you will not see the on indication)
4. with shift pressed right click on the character who does not want romantic actions and click “Change to SP”.
5. then in the character editor on the top left click on the 3 dots and in the orientation section select that the sim likes men or women.
I have something similar. My sims is a spellcaster and used the potion to have the romance bar maxed out with sims he wanted. I choose a sim which i know had the correct sexual orientation, used the potion and choose the option (cant remember how its call) under the romantic category. They have zero friendship, but full romance maxed and I tried different things, actually all the options, and nothing worked. I though it was odd because I know how this game work and you generally better start with light interaction, like complimenting their self, flirting etc... but it was not working. She rejected everything, then I looked and they had a awful compatibility... that being said, two sims with awful compatibility are normaly able to woohoo or kiss or whatever... then I pop in CAS to see whats her preferences/likes and make sure the sexual orientation is good. Checked sexual orientation, all good, check the likes/dislikes and she had only one randomly set for the type of interaction she dislike and that was it, nothing but apparently this only one like/dislike made them uncompatible, even though it had nothing to see with the romantic interactions types... So I gave her a bunch of those likes/dislikes, and gave her that she liked romantic, flirt and intimate interactions... She turns out to have a good compatibility and then it worked... it was odd... because I had sims with bad compatibility previously being able to have woohoo and romantic interactions with my sims in the same kind of circumstances where they have only a couple of likes/dislikes... to me its a bug.
