R Shiny slider and plot are not populating on Linux RedHat. Any idea what's going on?

Question

I'm trying to host a shiny app on a Linux RedHat server. The app works perfect when running locally. However, neither the slider or histogram is showing while on the server. A text box is populating where the slider should be.

The ui.R and server.R scripts are located here on the server: /srv/shiny-server/myapp

Config file is located here on the server: /etc/shiny-server

Any idea what's going on? Any help is appreciated. Thanks!

The code is below:

ui.R:

Sys.setlocale("LC_NUMERIC", "C")
options(shiny.trace = TRUE)
# Define UI for app that draws a histogram ----
ui <- fluidPage(

  # App title ----
  titlePanel("Hello Shiny!"),

  # Sidebar layout with input and output definitions ----
  sidebarLayout(

    # Sidebar panel for inputs ----
    sidebarPanel(

      # Input: Slider for the number of bins ----
      sliderInput(inputId = "bins",
                  label = "Number of bins:",
                  min = 1,
                  max = 50,
                  value = 30)

    ),

    # Main panel for displaying outputs ----
    mainPanel(

      # Output: Histogram ----
      plotOutput(outputId = "distPlot")

    )
  )
)

server.R:

# Define server logic required to draw a histogram ----
server <- function(input, output) {
  
  # Histogram of the Old Faithful Geyser Data ----
  # with requested number of bins
  # This expression that generates a histogram is wrapped in a call
  # to renderPlot to indicate that:
  #
  # 1. It is "reactive" and therefore should be automatically
  #    re-executed when inputs (input$bins) change
  # 2. Its output type is a plot
  output$distPlot <- renderPlot({
    
    x    <- faithful$waiting
    bins <- seq(min(x), max(x), length.out = input$bins + 1)
    
    hist(x, breaks = bins, col = "#75AADB", border = "white",
         xlab = "Waiting time to next eruption (in mins)",
         main = "Histogram of waiting times")
    
  })
  
}

Config file:

preserve_logs true; 
# Define the user we should use when spawning R Shiny processes
run_as shiny;

# Define a top-level server which will listen on a port
server {
  # Instruct this server to listen on port 3838
  listen 3838;

  # Define the location available at the base URL
  location / {
    # Run this location in 'site_dir' mode, which hosts the entire directory
    # tree at '/srv/shiny-server'
    site_dir /srv/shiny-server/myapp;
    
    # Define where we should put the log files for this location
    log_dir /var/log/shiny-server;
    
    # Should we list the contents of a (non-Shiny-App) directory when the user 
    # visits the corresponding URL?
    directory_index on;
  }
}