Legend is not saved in html

[vasya-paradiz]

Hi,
I create a map using add_grid, and I can see the legend in the viewer of R-studio but when I save it as html, the legend disappears.

Here is my code:

bb <- mapdeck(token = key,pitch = 20,
          location =  c(12.8262, 56.049), # middle point of Helsongborg map
          # location =  c(12.8262, 56.040), for pitch 30
          zoom = 10.4,
          style = mapdeck_style('streets')
  ) %>%
    add_polygon(   # adding shape layer
      data = chi_shape
      ,fill_colour = "#49fc0350" 
      , stroke_colour = "#340163" 
      , stroke_width = 100 
      ,update_view = FALSE 
    )  %>% add_grid(data = as.data.frame(res3), lat = "lon", lon = "lat", 
                    elevation = "p_tonns", elevation_scale = 4,
                    cell_size = 500,
                    elevation_function = "max",
                    colour_function = "max",
                    colour = "p_tonns",
                    layer_id = "tree",
                    extruded = T,
                    legend = T,
                    legend_options = list(title="Tons"),
                    update_view = F) %>%
    add_title(title = paste0(i,", production by zone (tons)"))

  file_html <- "file name"
  saveWidget(bb, file_html)

I also tried to save html using mapshot but the result is the same.

So then I get this map in the viewer:

But when I open it in Chrome or Edge, I get this:

zooming-in / out or moving the map does not help, still no legend.

When I open Chrome console, there is no error, and it has the legend container:

In the same script I create another map using add_line, and in that case the legend works

I use
mapdeck_0.3.4
R version 4.1.0 (2021-05-18)
Platform: x86_64-w64-mingw32/x64 (64-bit)
Running under: Windows 10 x64 (build 19044)

[Dave]

Reprodicible example

library(mapdeck)
set_token(secret::get_secret("MAPBOX"))

df <- read.csv(paste0(
	'https://raw.githubusercontent.com/uber-common/deck.gl-data/master/',
	'examples/3d-heatmap/heatmap-data.csv'
))

df <- df[ !is.na(df$lng ), ]

mapdeck( style = mapdeck_style("dark"), pitch = 45 ) %>%
	add_grid(
		data = df
		, lat = "lat"
		, lon = "lng"
		, cell_size = 5000
		, elevation_scale = 50
		, layer_id = "grid_layer"
		, auto_highlight = TRUE
		, legend = T
	)

[Dave]

I've no idea why this happens. It looks like the .legendContent isn't being kept when exporting from RStudio to the browser. But I don't know why.