Not that I can think of, but then I don't really define myself by my gender or race or really give much time to identity politics in general.

May I posit this is because you are rarely in situations where you feel your gender is pronounced? If you were, say, a man applying for a job as a general hospital nurse, you would feel this, or as a heterosexual hairstylist applying for a salon job. There are stereotypes you would feel pressure to justify why you, who do not fit the stereotype, would be a beneficial person to hire, in such cases.

Not defining oneself by gender or race does not invalidate the hypothesized effect: that one may feel excluded if they don't see anyone like them doing it. There is no denying that the fact of being a man or woman influences a lot of our lives and how people treat us.

I felt uneasy in my college electives composed almost entirely of women.

I imagine I would have loved that.

> Have you never felt intimidated/uneasy when entering a group situation in which every other person was a particular race/gender/age group to which you don't belong?

Even if you have, that's problematic on your part. Just because people look differently doesn't mean they won't be welcoming towards you, that's tribalism at it's finest and needs to stop.

The ones that do feel intimidated/uneasy about it need to work on their own perception of other people and not the other way around. You don't change the mindset of a group because there isn't any, it only exists on paper in your gender studies textbooks. Humans are individuals and everyone has their own mindset regardless of genitalia, skin color, age etc. Thinking otherwise is both disrespectful and racist/sexist/agist.