Plotly in R: Markers oscillate behind background polygon when markers are animated

I am using plotly in R to animate markers that should be plotted in front of a polygon. However, the markers move behind the polygon every other frame. I can set redraw = TRUE , but the markers still blink. Is there a way to stop this from happening?

A reproducible example where the markers are stationary but change size each frame:

set.seed(1002)
dat.polygon = data.frame(x = c(0,0,1,1), 
                     y = c(0,1,1,0))
dat.marker = data.frame(id = rep(seq_len(5), 10), 
                    x = rep(runif(5, 0, 1), 10) , 
                    y = rep(runif(5, 0, 1), 10), 
                    f = rep(seq_len(10), each = 5), 
                    r = runif(50, 1, 10))

plot_ly(x = ~x, y = ~y) %>%
  add_polygons(data = dat.polygon, alpha = I(1)) %>%
  add_markers(data = dat.marker, frame = ~f, ids = ~id, size = ~r) %>%
  animation_opts(frame = 1000, transition = 500, redraw = FALSE)