You said the partnership was specified it would operate under Missouri law. What makes you believe washington state is an available venue for your suit? Are you expecting the to apply Missouri laws to a washington based suit?

i don't see any action you have against the bank. Your lack of definition within your own partnership is the cause of your issues. They are simply saying they are not going to arbitrarily enforce your lack of being able to properly designate a person to have a controlling role in your business so you either all present an issue with all parties in agreement or the partnership battle it out in court and the bring the results from the court as to who controls what.

no, you cannot simply sue for 1/3 of what is in the bank. You own 1/3 of a business. That money in the bank is not "the business". The business is the aggregate of all assets, debts, liabilities, and receivables.