Setting anchor = "free" in R subplot() causes the graph to disappear

I'm trying to build a subplot of stacked scatter plots, where there are multiple axes on each scatter plot.

Below is an example of the type of plot. To position the yaxis side-by-side, I have layout(yaxis(anchor = "free")) set am using position to place the axis.

All my attempts to set anchor = "free" in subplots left my plot space completely blank. Some testing revealed that even a subplot constructed from a single plot will not display if anchor="free"

Please see below REPREX.

require(plotly)
df <- data.frame(x = 1:10, y = 1:10, y2 = 10:19)
plt <- plot_ly(data = df) %>%
  add_trace(x = ~x, y = ~y,
            mode = "markers", type = "scatter",
            yaxis = "y") %>%
  add_trace(x = ~x, y = ~y2,
            mode = "markers", type = "scatter",
            yaxis = "y2") %>%
  layout(
    xaxis = list(
      domain = c(.12, .88)
    ),
    yaxis = list(
      title = "y_1"
    ),
    yaxis2 = list(
      title = "y_2",
      anchor = "free",
      position = .10,
      overlaying = "y"
    ),
    margin = list(
      pad = 60
    )
  )
subplot(plt)

Führen Sie zunächst das bereitgestellte R-reprex mit plot_ly(), layout() und subplot() aus, um zu bestätigen, dass anchor = "free" einen leeren Plot erzeugt. Verfolgen Sie anschließend, wie subplot() die Einstellungen für yaxis und yaxis2 verarbeitet, insbesondere anchor, position und overlaying. Als abgeschlossen gilt die Aufgabe, wenn der Subplot seine Traces rendert und dabei die frei positionierte Achse beibehält.