layout.shapes.legendgroup is unexpectedly non-functional

layout.shapes.legendgroup is non-functional although included in the official reference (https://plotly.com/r/reference/layout/shapes/)

In the below reprex, I have set all objects to the same legendgroup. I would expect them all to disappear when clicking on the legend but this does not happen.

library(plotly)
x <- seq(-2 * pi, 2 * pi, length.out = 1000)
df <- data.frame(x, y1 = sin(x), y2 = cos(x))

fig <-
  plot_ly(df, x = ~x) %>%
  add_lines(y = ~y1, name = "A", legendgroup = "B") %>%
  add_lines(y = ~y2, name = "B", legendgroup = "B")

fig %>% 
  plotly::layout(shapes = 
                   list(
                     list(type = "rect",
                          fillcolor = "blue", line = list(color = "blue"), opacity = 0.3,
                          x0 = -1, x1 = 1, xref = "x",
                          y0 = -0.5, y1 = 0.5, yref = "y", legendgroup = "B")))

Example adapted from https://plotly.com/r/dropdowns/

Start by running the provided R reprex and compare the shape's legendgroup behavior with the two line traces. Use the layout.shapes reference as the expected behavior; done means clicking the shared legend entry hides and shows the shape together with the grouped traces.