You have people writing design documents and other people implementing them. You have an idea of a finished product that it sounds like you've been working towards for over a year with no meaningful iteration on product. You have bugs that come up within an iteration and the people who worked on the story aren't stopping and fixing them. You have limited test coverage, so meaningful refactoring becomes hugely more difficult.

I'd also suspect that the business side has no real visibility into where you are in relation to their goals.

You're trying to do agile with a huge portion of your team still doing waterfall. Waterfall can work - but it can't coexist with agile on the same project.

My plan if I were in control of your organization:
Fire the existing contractors. Find a PM who can relate business requirements to developers, and technical requirements to businesspeople. Hire developers you trust to implement the product without an architect to tell them how to do it. Figure out what your MVP is. Slice that into stories, do those, and decide what's the next thing that would add the most value to the product.

Presumably you can't do all of that. If I were you, I'd work towards isolating myself in a group small enough to make meaningful progress without interference from everyone else. It's kind of opposite of my advice last time, but your team doesn't seem to be interested in drinking the water/kool-ade, and no amount of process will fix that.

Matthew