Yes they did, according to a reddit post by AnUnearthlyGay. The BBC responded to their complaint about this saying
a small section of dialogue was not included because it didn't provide the accuracy of language we need for our young audience, specifically a definition of the meaning of 'non-binary' which was given by one of the characters.
The definition given by one of the characters was, presumably
People who aren't female or male.
The BBC hav An A-Z of LGBTQ+ language for speaking to your child which includes
Non-binary
'Non-binary' is typically used when someone doesn’t identify exclusively as male or female, although the term is used by different people in different ways.
Some non-binary people may have an internal sense of gender identity that encompasses both genders, whereas others may have no internal sense of gender at all. Again, it’s fine to ask your child to tell you more about what this means to them and how they feel.
So the BBC appear to prefer a definition that encompasses a more inclusive, wider range.
The quoted BBC response goes on to say
We left in dialog where characters discuss their pronouns which makes it clear that they don't identify themselves according to binary gender beliefs.