One thing I found out is that although they are sold as interchangeable and all the same size from brand to brand and model to model, the dimensions on plates are all slightly different. I've never had a brass button not fit, but certainly the dimensions of Arca plates vary.
Are you sure the brass button is too big and not just slightly off center?
I gave up on cheap arca gear and went with one brand so they are all pretty similar from glass to glass.