Yes - why are these adjectives even coming up at all? There are alternatives that would probably make your point in a succinct manner without being sexist.
Yeah I think it’s fair to say that in many circumstances people would use masculine as a pejorative and not get called out for being sexist. There’s some historic power imbalance stuff at play there, but it’s still sexist.
If you have problems with some type of behaviour it’s much better to say exactly what they are rather than appealing to some platonic notion of sex characteristics, which is both offensive and poorly communicates your position.
Is it?
To answer this, just reverse the genders in the statement and see if it's still sexist.
"It's very masculine and obviously doesn't work that well"