Some are more subjective to the state of intended concentration.
I attended a Stress Relaxation session through employment where hypnosis was used. I was unable to be hypnotised while other’s had no issue with this. Personally I didn’t feel the need to be hypnotised and this wasn’t why I initially attended. Well, it was described as I mentioned, as Stress Relaxation. So I had minor reservations once understanding this was part of the theropy. So it was probly due to my unwillingness to go along with something I didn’t care to do to begin with.
In other words you can be hypnotised if your mind is open to the very idea of being hypnotised. If your closed to the very idea from the on-set? Then its not probable though not impossible. My impression from what I witnessed, is that some attempt at willingness has to be present.
Then again maybe this particular therapist wasn’t as good as another might be? Just a brief encounter I had with this so I’m not the best to speak on this either