Shiny uiOutput and updateSelectInput interaction

Hi together,
I am trying to generate a user interface that allows the user to select first a plot type (e.g. XY, hist...) and then get a plot type specific set of input fields to further customise the plot (e.g. select the column for the histogram...).
I first generate the plot type specific settings with uiOutput and then populate the input elements based on the dataset (in the example iris). This works for the first time a plot type is selected or the app is started, but once the uiOutput is called again the input elements are no longer updated.
Below is my example code:

library(ggplot2)
library(stringr)
dataSel <- c("Full Data")
plotTypes <- c("XY", "Hist", "Box", "Matrix")
AxisScale <- c("lin", "log")
ui <- fluidPage(
titlePanel("Data Viewer"),
  sidebarLayout(
   
    # Sidebar panel for inputs ----
    sidebarPanel(h3("Input Files"),
                 "Selected Plot Type:",
                 textOutput("control"),
                 width = 2
    ),  # end sidebar
    
    # Main panel for displaying outputs ----
    mainPanel(
      
      tabsetPanel(type = "tabs",
                  tabPanel("Plots", 
                           fluidPage(
                             fluidRow(
                               column(
                                 5,
                                 hr(style = "border-top: 0px solid #000000;"),
                                 wellPanel(
                                   tags$head(tags$style(HTML(".selectize-input {height: 11px; font-size: 10px}"))),
                                   style = "width: 760px",
                                   fluidRow(h4("Plot 1")),
                                   fluidRow(
                                      column(3, selectInput("DataSource.plot1", h6("Data Source:"), choices = dataSel, selected = NULL)),
                                      column(2, selectInput("PlotType.plot1", h6("Plot Type:"), choices = plotTypes, selected = NULL)),
                                      column(2, sliderInput("Limit.No.Points.plot1", h6("Max No Points"), min=1,max=100,value=100)),
                                      column(2, selectInput("Filter1.plot1", h6("Filter 1"), choices = dataSel, selected= NULL)),
                                      column(3, sliderInput("Filter1.range.plot1", h6("Range"), min=1, max=100, value=c(0,100)))),
                                   uiOutput("settings.plot1"),                 
                                   plotOutput("plot1", click = "plot1.click", dblclick = dblclickOpts(id = "ToOpenImage", delay = 300))
                                   
                                            
                                 ))))),
                  tabPanel("Tables", tableOutput("table"))
      )
    )
  ) 
)


################################### SERVER
server <- function(input, output, session) {

  # check the plot type
  output$plottype.plot1 <-reactive({input$PlotType.plot1})
  # check the input columns
  output$control <- renderText({ 
    input$PlotType.plot1
  })
  output$settings.plot1 <- renderUI({
    if(str_detect(input$PlotType.plot1, "XY"))
    {
    fluidRow(
      column(2, selectInput("Xaxis.plot1", h6 ("X axis:"), "", selected = NULL)),
      column(2, sliderInput("Xaxis.Range.plot1", h6 ("X axis range:"), min=1, max=100, value=c(0,100))),
      column(1, selectInput("Xaxis.Scale.plot1", h6("Scale"), choices = AxisScale, selected = NULL)),
      column(2, selectInput("Yaxis.plot1", h6 ("Y axise:"), "", selected = NULL)),
      column(2, sliderInput("Yaxis.Range.plot1", h6 ("Y axis  range:"), min=1, max=100, value=c(0,100))),
      column(1, selectInput("Yaxis.Scale.plot1", h6("Scale"), choices = AxisScale, selected = NULL)),
      column(2, selectInput("Color.plot1", h6 ("Color:"), "", selected = NULL))
            )}

    else if(str_detect(input$PlotType.plot1, "Hist"))
    {
      fluidRow(
      column(2, selectInput("Xaxis.plot1", h6 ("X axis:"), "", selected = NULL)),
      column(3, sliderInput("Xaxis.Range.plot1", h6 ("X axis range:"), min=1, max=100, value=c(0,100))),
      column(2, selectInput("Yaxis.Scale.plot1", h6("Y scale"), choices = AxisScale, selected = NULL)),
      column(2, selectInput("Group.plot1", h6 ("Group by:"), "", selected = NULL)),
      column(3, sliderInput("No.bin.plot1", h6 ("No bins:"), min=1, max=100, value=10))
    )}
   else if(str_detect(input$PlotType.plot1, "Box"))
    {
     fluidRow(
      column(2, selectInput("Yaxis.plot1", h6 ("Values:"), choices ="", selected = NULL)),
      column(3, sliderInput("Yaxis.Range.plot1", h6 ("Y axis range:"), min=1, max=100, value=c(0,100))),
      column(2, selectInput("Yaxis.Scale.plot1", h6("Y scale"), choices = "", selected = NULL)),
      column(2, selectInput("Box.Category.plot1", h6 ("Category:"), choices ="", selected = NULL))
     )}
    else if(str_detect(input$PlotType.plot1, "Matrix"))
    {
      fluidRow(
        column(2, selectInput("FacetX.plot1", h6 ("Facet X:"), "", selected = NULL)),
        column(2, selectInput("FacetY.plot1", h6 ("Facet Y:"), "", selected = NULL)),
        column(2, selectInput("MatrixType.plot1", h6 ("Type:"), "", selected = NULL)),
        column(2, selectInput("MatrixValue1.plot1", h6 ("Value 1:"), "", selected = NULL)),
        column(2, selectInput("MatrixValue1.plot2", h6 ("Value 2:"), "", selected = NULL))
      )}
  })
  

  data <- reactive({iris})
  updateSelectInput(session, inputId = "Xaxis.plot1", choices = names(iris), selected = names(iris)[1])

    output$table <- renderTable({iris})

    output$control <- renderText({names(iris)})
    
  reactive.plot1 <- reactive({gplot <- ggplot(data())})
  
  output$plot1 <- renderPlot({reactive.plot1()})
  }
shinyApp(ui, server)

Thanks for the help.