This is way above my head, but I've been following the topic to the degree I can. It seems that part of the problem is getting funding to properly test it while controlling for confounding factors and that data is slow to come because vacuum chambers tend to eat their electronics and they have to tune the thruster to have a enough thrust to be detected with the facility they hope to use.
I vaguely understand there's some strange non-linear stuff going on with the power in and the expected thrust and I think from what's said that the shape or nature of the cavity figures in here somehow. I was trying hard, but that's the best I could do. I may well be very smart, but this takes math and facts and stuff. So I'm frustrated. Because the science reporters explaining this don't really. I mean ... I can handle a few lumps in my pablum.
I wish I had the ability to casually throw a few hundred thousand dollars their way in the service of pure curiosity. Never mind what it means for space exploration although that's that's huge if it works. Maybe that's what has everyone scared, because once you are out of the atmosphere - the tech itself doesn't seem to be all that challenging. It's the implications.
But back to the testing and finding out if this is real or not, and what the hell is going on. No matter what the outcome, it has to be fundamentally interesting. You don't generally see a chance to resolve interesting questions like that for sums less than fractions of a gross domestic product. So the most confusing thing to me is why they aren't drowning someone in money.