geom_line() with text mapping and without group mapping doesn't render

I have a base-barchart plot with working tooltips.

I want to add a line-chart by clicking a radioButton on top of the barchart, also with hovering tooltips, which is not working as I expected.

1. When adding a text argument to the additional line, the line is not showing up, but when I hover over the pot, the labels of the line show.
2. When uncommenting the text argument (line 28), the line shows, but no hovering tooltips, as expected.
3. When removing the tooltip = "text" from the ggplotly call (line 33), the line and the tooltips shows up, but the formatting is not like I want it to be.

library(shiny)
library(ggplot2)
library(plotly)

dfN <- data.frame(
  time_stamp = seq.Date(as.Date("2018-04-01"), as.Date("2018-07-30"), 1),
  val = runif(121, 100,1000),
  col = "green", stringsAsFactors = F
)

ui <- fluidPage(
  br(),br(),
  checkboxInput("zus1", value = FALSE, label = HTML("add Line")),
  plotlyOutput("plt")
)

server <- function(input, output, session) {
  output$plt <- renderPlotly({
    key <- highlight_key(dfN)
    p <- ggplot() +
      geom_col(data = key, aes(x = plotly:::to_milliseconds(time_stamp), y = val, fill=I(col),
                               text=paste("Datum: ", time_stamp, "<br>")))
    
    
    if (input$zus1 == TRUE) {
      p <- p + geom_line(data = dfN, aes(x = plotly:::to_milliseconds(dfN$time_stamp), y = val
                                         ## This text is not showing up, but hovering shows the labels
                                         # , text=paste("Value: ", val)
                                         ), color="red")
    }
    
    ## Removing tooltip = "text" shows the additional line and hover-labels but with horrible formatting.
    ggplotly(p, source = "Src") %>% 
      highlight(selectize=F, on="plotly_click", off = "plotly_doubleclick", color = "blue") %>% 
      layout(xaxis = list(tickval = NULL, ticktext = NULL, type = "date"))
  })
}

shinyApp(ui, server)

Beginnen Sie mit dem bereitgestellten Shiny-Beispiel und konzentrieren Sie sich auf die geom_line-Textzuordnung sowie den Aufruf ggplotly(p) mit tooltip="text". Stellen Sie den Fall nach, in dem die Linie ausgeblendet wird, ihre Beschriftungen jedoch angezeigt werden, und ermitteln Sie anschließend, durch welches Verhalten die Linie und korrekt formatierte Hover-Tooltips gemeinsam gerendert werden.