I think this is discussion rather than support. Once again I discover that I don’t know how much I don’t know.
I converted my cabling system to stop the cross talk problem (and thanks again for explaining). The new issue is that on 2 of my 8 neopixel strips, off is not off. Using either the pot that controls brightness (set to zero) or software to set the color to Black, the strips have a low level glow on the blue LED channel. On the other 6 it works fine - off is off. I’m running on an arduino mega, and the two problem pins involved are 43 and 47.
The problem does not occur using the same physical system and software based on the adafruit library for the same functionality. Obviously the code is different, so a bug is entirely possible. However, the problem is eliminated running my FastLED version but using different pins.
So I have a couple of questions. Is there anything special about those two pins (in general)? If something is wrong with the pins, why would it show up running FastLED, but not running the adafruit version?