Axis labels for NA-Data with factor levels

When having a NA-Dataframe, but correct facor levels for x and y, the created empty plot does not label the axis according to the factor levels.

In the following example I'd expect an empty plot with axis labels "Entry 1" and "Entry 2" on the x and a range of about [0; 20] on the y axis

data <- data.frame(a = factor(NA, levels = c("Entry1", "Entry2")), b = factor(NA, levels = c(1:20)))
plot_ly(data, x = ~a, y = ~b, type = "bar")

also:

data <- data.frame(a = factor(character(), levels = c("Entry1", "Entry2")), b = factor(numeric(), levels = c(1:20)))
plot_ly(data, x = ~a, y = ~b, type = "bar")

issue に示されている因子レベルを使用して、plot_ly で両方の例を再現し、その後、棒グラフの軸に対して空のデータまたは NA データがどのように処理されるかを追跡します。完成した動作で x 軸に Entry1 と Entry2 のラベルが付き、y 軸の範囲が約 0 から 20 になることを確認します。