I just ran into rather odd issue. It's not a FastLED problem, but I'm wondering if anyone has seen this before.
For my current project, I have six parallel four foot LPD8806 strips. I'm sitting off to the side as I work on the programming (they are on the floor). I noticed that when I did fill_solid with certain colors, the colors were slightly different every other strip (in other words, strips 1,3, and 5 looked the same, and strips 2,4, and 6 looked the same but 1 looks slightly different than 2). At first I just figured I got strips from two different batches, but then I realized that I had extended each of the strips by six LEDs and the extensions all came from the same 1 meter strip, and yet I did see any color changes within an individual strip.
I switched the first and second strips, and everything still looked just like it did before the switch. I was trying to see if I could take a photo to post here, but then I noticed something else that really surprised me. When I stood directly over the strips, they all looked the same color. It's only when I'm off to the side that this happens. Something else I should mention is that the strips are wired serpentine.
Has anyone else seen something like this? Any idea of what is going on? I may end up building a bunch of four-conductor extension cables and run all the strips the same direction, but I’m still curious about this.