plotly_click + ggplot bug?

app.R

library(plotly)
library(shiny)

mtcars$key <- row.names(mtcars)
mtcars$col <- "black"
mtcars$name <- row.names(mtcars)

ui <- fluidPage(
  plotlyOutput("plot")
)

server <- function(input, output, session) {
  output$plot <- renderPlotly({
    p <- ggplot(mtcars, aes(x = gear, y = name, key = key)) + 
      geom_tile(aes(fill = mpg, key = key))
    
    ggplotly(p) 
  })
  
  observeEvent(event_data("plotly_click"), {
    click_data <- event_data("plotly_click")
    print(click_data)
   
  })
}

shinyApp(ui, server)