I think it may be bugged, yes. I did the camp celebration scene and was only able to "think about" someone. I had gotten the Karlach and Shadowheart "first kiss" scenes already so, if the above comment about only having one intimacy scene is correct then that would make perfect sense. However, I had not gotten Lae'zel's scene yet. She had already expressed interest and said she would drop by on some night, and during the party basically told me she was turned on. But when I went to bed, nothing happened -- further, the narration if I chose to think about her suggested that the scene had already happened (something something aches and bruises).
The kicker is that I found that if I rest twice before returning to the grove for the party, I get two consecutive event scenes and the second of them is Lae'zel's first sex scene. So the conditions for it to happen have clearly been fulfilled by the time the party rolls around, but it seems like if Lae'zel's sex scene is "in the queue", as it were, then the party treats it as if it had already happened.
I also didn't get any scene with Lae'zel after the party. Not only that, but when it was time for the next romantic scene (and she woke me so we could fight), that cutscene was skipped too! In the morning she was just stuck at her tent in her combat pose, lol.