Is phenomenalism counter-intuitive?

Hello, I think phenomenalism is counter-intuitive because they deny the idea of existence that is external or not a part of the mind, which I find illogical because the belief that all what is just part of the mind implies the existence of the mind which further implies existence itself as something external to the mind. I apologize for I probably used informal terms, I hope you all understood what I am trying to say. Thank u so much 😊