Unable to style colorbar in density mapbox

[banamwana]

I am following the example given here: https://plotly.com/r/mapbox-density-heatmaps/

However, I am unable to change the color of the coloraxis (or use showscale = F or move the colorbar over on x).

The plot won't work unless coloraxis = 'coloraxis' is specified, and there doesn't seem to be a way to style the coloraxis.

# population density available from https://data.humdata.org/dataset/worldpop-population-density-for-haiti
pop_den <- read.csv(data_path)
plot_ly() %>% 
  add_trace(
    data = pop_den,  type = 'densitymapbox',  lat = ~Y,  lon = ~X,  z = ~Z,
    coloraxis = 'coloraxis',
    radius = 10) %>% 
  layout(
    mapbox = list(
      style = "carto-positron",
      zoom = 6.5,
      center = list(lon = -73.09, lat = 19.06),
      coloraxis = list(colorscale = "Grey", colorbar_x = 1.5)
      )
    )