pies and subplot not working as expected

Based on this StackOverflow post, it seems pie charts are not working as I would expect with subplot. I will admit though that this is my first ever attempt at pie charts in Plotly. I did verify by inspecting DOM that both pies do exist in the examples below.

    # devtools::install_github('ropensci/plotly")

    library(plotly)
    ds_r <- data.frame(labels1 = c("Baseline", "DTC", "Detailing", "Flex"),
                       values1 = c(63.5, 8.5, 20.6, 7.4))

    ds_l <- data.frame(labels2 = c("Baseline"),
                       values2 = c(100))

    p <- plot_ly(
      ds_r, labels = ~labels1, values = ~values1, type = "pie", 
      showlegend = F
    )

    p2 <- plot_ly(
      ds_l,labels = ~labels2, values = ~values2, type = "pie", 
      showlegend = F
    )


    subplot(p, p2, nrows = 1)

empty axes

    # devtools::install_github('ropensci/plotly")
    # an "empty" plotlyjs axis for layout
    emptyAxis <- list(
      title = "", 
      zeroline = FALSE,
      showline = FALSE, 
      showticklabels = FALSE, 
      showgrid = FALSE
    )

    p <- plot_ly(
      ds_r, labels = ~labels1, values = ~values1, type = "pie", 
      showlegend = F
    ) %>% layout(xaxis = emptyAxis, yaxis  = emptyAxis)

    p2 <- plot_ly(
      ds_l,labels = ~labels2, values = ~values2, type = "pie", 
      showlegend = F
    ) %>% layout(xaxis = emptyAxis, yaxis  = emptyAxis)


    subplot(p, p2, nrows = 1)

Start by running the two reproducible examples using plot_ly() and subplot(), with and without the empty axes layout. Trace how subplot() assigns pie traces and axes; done means both pie charts render correctly side by side without requiring empty axes.