Thanks for your response. I am not only using relief to set the action btw. The action is largely set, to the lowest possible, when I adjust the bridge to just make the high notes playable. If the relief was correct at that point, I'd be finished and the action would be nice and low.
I had read, and tried doing the setup in the order you use. The trouble was, there are varying opinions about relief, and I had not read anywhere of the problem that too much relief can cause. So by setting the relief, just a little too much, and then adjusting the bridge to set the action at the 12th fret, I ended up with trouble at the high frets with the notes buzzing and even fretting out completely. We even had a discussion here about tapering high frets off.
The only thing I am really doing differently is to determine the minimum bridge height for playability at these high frets. You can do this because these frets are typically in the part of the neck that's clamped to the guitar body, or near it, so the string tension and truss rod don't put any relief into them at all.
Funnily, I purchased a cheap secondhand archtop acoustic a little while ago, and someone had attempted to set it up, and ended up with the exact problem I described above. The high frets were all buzzing and fretting out. So I quickly set the bridge a little higher to stop the buzzing, then a quarter turn on the truss rod brought the action back down and the guitar is one of the lowest action acoustics I own