1 led = 3 led?

I have a weird anomaly with a WS 2811 12 v strip. I have a strip with 100 LEDs. For every one LED I add under Led Preference it lights up 3 on the strip.
eg

  • So if my LED preferences say 3 under Length, 9 LEDs light up.
  • If I 10 in length, 30 will light up.

Is that normal?

WS2811 has one IC that controls 3 LED, thus you can only address groups of 3 LED.

That’s a side effect of that particular 12V strip. They combine 3 LEDs in series to get closer to 12V.
Other strings use a different controller and/or onboard regulator for each LED.

You’ll have to research what you’re buying to know for sure.