Thanks for sharing your experiences!
FWIW, I've only seen this problem with core Custom 24 PRS's. My experiences with this model have just been an exercise of frustration. It's like, they almost built a great guitar. So many things right, yet one annoying thing consistently not right. At least that's been my experience over 28 years of trying to like this model. Trems, stoptails, regular, wide/thin, pattern, old strings, new strings, different pickups, 9's, 10's, 11's, it just doesn't seem to matter - I almost always get the same results when I play that note on a CU24.
What set me off on this topic was that I visited a local store yesterday with the intention of trying and hopefully buying a drop dead gorgeous 35th Anni CU24. Open the case = stunning. Pick it up = lightweight and well balanced. Play a few chords and notes in the first 5 frets of the guitar = awesome. Go up the neck = great. Play the B note on the 12th fret B string, and...
There it was again, the curse of the CU24.
A dead spot.
Arggh...