Similar with scientists in my experience. Though it's more easily explained as the older generation sees the terms as interchangeable or not worth arguing about. The younger generation tends to use sex specifically and might call out improper use of gender.

// "MICE DON'T HAVE GENDER!!!!" <- something I've heard at high volume too many times

Interesting the way it changes within a couple of generations, the "older generation" in my day, i.e. my dad - a linguist - would call out the then-modern interchangeable usage, by insisting "nouns have a gender, people have a sex!"

I wonder why that is.