I have noticed the same dead spot on Fender basses and Thunderbirds. My EB-2, the 2001 Thunderbird, the fretless 'Bird, and the FenderBird do not seem to have any. I have not noticed one on the 2013 EB, and the dead spot is minimal to the point that it is sometimes there, sometimes not on the 2015 and the FlamingoBird, a 1991. The Ric I had was completely dead around the seventh fret on the G string. Tweaking it helped, but it didn't go away.
Point being that setup makes a difference, the individual bass makes a difference, but I am not convinced that the way the bass is built matters when it comes to dead spots.
My MIM P is weak at C on G. Not dead. It’s weak at C# on my Deluxe Precision. The ‘15 and the NR have a barely perceptible weak spots at the same place, but I can’t really notice them. My bolt-ons are the same, The Goth maybe being the most noticeable of the three. None of them bother me. And you have to go listening for them to even know about them. I suppose if it was really noticeable on a bass, I might be discouraged with it, but none of my basses bug me like that.
My Foundation is the only bass I have that I can truthfully say has no difference in resonance or sustain on any note on any string. The neck on it amazing.
brown 