geom_line becomes invisible when color aesthetic applied

I am attempting to apply a gradient color scale to a line in a ggplot object. When I create the plotly chart, the plotted line is not visible. Hovering over the plot area shows the values of the variables if the cursor is where the line is located, even though the line is not visible.

If I do not apply a color aesthetic, the line is visible.

I have download the most recent plotly package from Github.

Here is some example code of the issue:

library(tidyverse)

df <- tibble(
x = rnorm(100, 7, 1),
y = rnorm(100, 4, 1),
z = rnorm(100, 5, 1))

plot <- ggplot(df) +
geom_line(aes(x, y, color = z),
lwd = 1.5) +
scale_color_gradient(low = "red",
high = "blue")

plot

plotly::plotly_build(plot)

ggplot:

Inizia eseguendo l'esempio R della issue con ggplot2, geom_line(), scale_color_gradient() e plotly::plotly_build(plot), confrontandolo con la versione senza un'estetica del colore. Traccia la conversione della linea ggplot colorata nel grafico Plotly; il lavoro è completato quando la linea è visibile mantenendo i colori sfumati e i valori al passaggio del mouse.