Funny you mention the
bugged owlbear cub encounter, because it is also where I first noticed this behavior with approval being distance based even in the camp itself

So since this bug allows us to redo the feeding scene, I brought every companion individually and gained approval with all. Which sucks, because approval in my opinion should apply to every companion globally while in the camp. But even when exploring, a companion that slightly wonders off may not be pulled into a dialogue scene and then misses out on approval. I feel like it should simply be a global thing regardless of distance.
Also I am not entirely sure as I didn't dig deep enough into the matter, but I believe approval also has a maximum limit for each scene. As I often notice that despite having all companions right next to me during camp scenes, not all of them will gain approval, even though I know they should.