ColorScale Will Not Change If Specifying with colorscale = c('hexcode1', 'hexcode2')

Hi,

After following the guide here, https://plotly.com/r/3d-scatter-plots/, I found that, when specifying color scale with colorscale = c('hexcode1', 'hexcode2') will not have changes to the color scale, yet the default palette names such as 'Rainbow' will work. In this case, it would not be possible to self-define the 2 end points of the color scale. Please feel free to run the R codes below to see what I mean.

library(dplyr)
library(plotly)

fig <- plot_ly(mtcars, x = ~wt, y = ~hp, z = ~qsec,
               marker = list(color = ~mpg, 
                             #colorscale = c('#FF0000', '#00FF72'), 
                             #colorscale ='Rainbow',
                             colorscale = c('#132B43', '#56B1F7'),
                             showscale = TRUE))
fig <- fig %>% add_markers()
fig <- fig %>% layout(scene = list(xaxis = list(title = 'Weight'),
                                   yaxis = list(title = 'Gross horsepower'),
                                   zaxis = list(title = '1/4 mile time')),
                      annotations = list(
                        x = 1.13,
                        y = 1.05,
                        text = 'Miles/(US) gallon',
                        xref = 'paper',
                        yref = 'paper',
                        showarrow = FALSE
                      ))
fig

Just wondering if this is a bug or may be there needs some updates to the guide?

Thanks,

Start by running the supplied R example from the 3D scatter plot guide and compare the custom hexadecimal colorscale with the working Rainbow palette. Trace how colorscale is passed through plot_ly() and add_markers(). Done means the two specified endpoint colors visibly control the marker colorscale, or the guide documents the supported syntax.