Turns out the customer didn't read the (enormously expensive) SOW. They don't want the product, can't ingest its output, don't want to do the work necessary to implement it, and on a recent roadmap review listed its function as their absolute last priority. I am not sure whether there's been a change in management, or some salesperson talked really fast, or what.
I am trying to appreciate this as 'salary for nothing' and use the time to study for other things but it turns out that for me this is an anxiety-inducing and unhappy experience.