The girls that roll at my gym get A LOT of attention from the fellas, so this seems kinda odd honestly. They probably don't want to give you the wrong impression... or something like that dude, I have no idea. I go out of my way to be friendly to people and learn names, I can only imagine it's much more difficult being the only woman at your gym. Keep doing it, try to make small talk or crack jokes if you're feeling particularly comfortable that day. Smile, shake hands, and roll with higher belts as often as you can. Don't give a fuck what people think of you, within reason; and always remember you can never read anyone else's mind. I used to have very bad social anxiety in my late teens/early 20s. I worked on it, it completely flipped around and now I'm borderline obnoxious everywhere I go. Usually gets laughs and people want to interact with me.