Weemos D1 Mini and GPIO for Neopixel

I’m trying to use a D1 Mini ESP32 with a neopixel (WS2811) LED. When using other ESP32’s I use GPIO19. On the D1 mini when I use the pin labelled IO19 I’m not getting any life on my LEDs.

I don’t imagine anyone knows the pin mapping for these?

Pinout attached.

Aha, that's interesting. When I connect the data pin of my LEDs to IO5 on the D1 mini and set my sketch to use pin 5, it works. Same with 23.

I guess I can just change that variable when I'm flashing to a D1 mini, but I'd love to know how to flash to pin 19 on the mini if it's possible.