BluesBear, I am familiar with that, and lack of lube was the first thing I suspected (I bought the M431 NIB from a dealer, shortly after the model was introduced). I'm a veteran DA revolver shooter (luv my old S&Ws), and immediately ensured the internals (especially the bolt/bolt spring area) were lightly lubed with CLP; made no difference at all. I never fired it enough to "dirty" the internals; I estimate I only fired 150-200 rounds of factory ammo through it. I then tried to "outlast" the problem; dry fired the heck out of it at every opportunity; again, it won!
Catbird, I am also familiar with failure to fully release the trigger resulting in lock-up. I fire a lot of rounds through several different DA revolvers; Colt, S&W, Ruger an old Hi Standard Sentinel, and even another Taurus (M94). I've never had this experience with any of these, and my DA trigger work is pretty consistent . . .
I gotta conclude there was a timing issue with that specimen. I actually suspect that, as friction from rapid cycling caused some internal part(s) to expand slightly, the bolt didn't drop out of the notch before the hand began trying to rotate the cylinder.