The use of "guys" as a neutral address bothers me, but in part it just makes a relatively good test of respect: if after you repeatedly correct someone they continue to persist in using it, that tells you something about them.
It's just very clearly a gendered term, no matter local conventions around use, and if you are repeatedly asked to not use it by people who are in the group you refer to and you continue to use it anyways that says a lot.