Chase has its own policies and while you're frustrated, you need to understand what those are before you blame them for having those policies. I agree with others that your AU cards are going against you. Amex doesn't backdate AUs, so whenever you became an AU on the Gold is going to show as a new account as of that day. [Chase and Capital One backdate AUs, so if I ever want to add an AU, I do it after the 24 month mark of account opening.] With Chase, I've had an AU removed from one of my cards but I (not the AU) was the one who had to make the request, then AU followed up with the credit agencies to have it removed. If just saying you're not financially responsible for the card doesn't work for you, what I did is an alternative.
There's no problem getting approved as a sole proprietor, that's always been the way me and P2 have done it for the past five years. Pay attention to your total available credit line with Chase (<50%-60% total HHI) and your velocity. You don't need to have a business checking account with Chase.