We don't seem to be able to find it inside the physical brain, and not for a lack of trying. Just throwing emergent behaviour out there changes nothing, just like it doesn't for AI.
What would "finding it" mean, whether inside the brain or out? It's quite easy to perturb consciousness by messing with the pieces of the brain, via pharmacology, injury, electrical stimulation, etc. I'm not sure why we need to assign responsibility to a single specific component like microtubules. That seems like saying the axle is responsible for a car moving. Sure, not wrong, but not right or explanatory either.
There are observed differences in brain function between conscious and unconscious patients. What's wrong with that as an initial characterization of "consciousness in the brain"? The investigation of these "neural correlates of consciousness" is quite a rich research field in its own right
