Shinylive app doesn't render leaflet map tiles

Question

I am trying to move an r-Shiny app onto a website using the shinylive package. The app is exported to HTML and it is functional, except that a leaflet map that is embedded in the site does not render visual elements.

The contents of the app.R file:

library(shiny) # 1.8.0
library(tidyverse) # 2.0.0
library(DT) # 0.31
library(leaflet) # 2.2.1

static_dat <- data.frame(
  Name = letters,
  Level = factor(sample(LETTERS[1:4], 26, replace = T)),
  Var1 = runif(26, 0,10),
  Attrib1 = sample(c(T,F), 26, replace = T),
  Attrib2 = sample(c(T,F), 26, replace = T),
  Attrib3 = sample(c(T,F), 26, replace = T),
  longitude = -115:-90,
  latitude = 26:51
)

# Define UI for app that draws a histogram ----
ui <- shinyUI(fluidPage(
  # App title ----
  titlePanel("Variables"),
  # Sidebar layout with input and output definitions ----
  sidebarLayout(
    position = "right",
    # Sidebar panel for inputs ----
    sidebarPanel(
      sliderInput(inputId = "minVar1", label = "Minimum Var1:",
                  step = 0.5, min = 0, max = 10, value = 0),
      checkboxGroupInput("attribs", label = "Select Attribs", inline = T,
                         choices = c("Attrib1", "Attrib2", "Attrib3")),
      checkboxGroupInput("levs", "Select levels:",
                         choices = levels(static_dat$Level),
                         selected = levels(static_dat$Level)),
      plotOutput('plot',   height = "300px")
    ),
    # Main panel for displaying outputs ----
    mainPanel(
      tabsetPanel(
        type = "tabs",
        tabPanel("Map", leafletOutput("map", width = "100%", height = "700px")),
        tabPanel("Data", DTOutput("tbl"))
        )
    )
  )
))

# Define server logic required to draw a histogram ----
server <- function(input, output, session) {
  
  zoom <- reactive({
    ifelse(is.null(input$map_zoom), 5, input$map_zoom)
  })
  center <- reactive({
    if(is.null(input$map_center)){
      return(c(40, -100))
    }else{
      return(input$map_center)
    }
  })
  
  filt <- reactive({
    {filt <- static_dat %>% 
      filter(Var1 >= input$minVar1,
             Level %in% input$levs,
             
             ((Attrib1 & "Attrib1" %in% input$attribs) | !("Attrib1" %in% input$attribs)),
             ((Attrib2 & "Attrib2" %in% input$attribs) | !("Attrib2" %in% input$attribs)),
             ((Attrib3 & "Attrib3" %in% input$attribs) | !("Attrib3" %in% input$attribs)),
      )
    }
    return(filt)
  })

  output$plot <- renderPlot({
    hist_dat <- filt() %>% 
      pull(Var1) %>% 
      as.numeric(.)
    
    hist(hist_dat, xlab = "Var1", main = "Distribution of Var1", xlim = c(0,10))
    abline(v = mean(hist_dat), col = 'red', lwd = 1)
    abline(v = median(hist_dat), col = 'red', lty = 2, lwd = 1)
    legend("topleft", lty = c(1,2), col = 'red', bty = 'n',
           legend= c(paste0("Mean = ",sprintf("%.1f", round(mean(hist_dat), 1))),
                     paste0("Median = ",sprintf("%.1f", round(median(hist_dat), 1)))))
    legend("topright", lwd = 0, legend = paste0("n = ",length(hist_dat)),
           bty = 'n')
    
  })
  
  output$map <- renderLeaflet({
      leaflet(data = filt()) %>%
        setView(zoom = zoom(), lat = center()[1], lng = center()[2]) %>%
        addTiles() %>% 
        addMarkers(lng = ~longitude, lat = ~latitude, popup = ~Name) %>% 
        addProviderTiles("CartoDB.Positron", options = providerTileOptions(noWrap = TRUE))
  })
  
  output$tbl <- renderDT({
    datatable(data = filt(),
              options = list(scrollY = 500,
                             scrollX = 600,
                             deferRender = T,
                             scroller = T,
                             fixedColumns = F))
  })
}

# Create Shiny app ----
shinyApp(ui = ui, server = server)

The whole app works, visuals and all, when running via runApp("./app_folder/")

However, porting to HTML from the console (after loading shinylive and httpuv):

export(appdir = "./app_folder/", destdir = "./docs")
runStaticServer("./docs")

Now the app works serverless, except the visual elements of the map, which just appears as an 'interactive' grey box.

I am perhaps missing a step in compiling this shinylive app or is there a problem with the leaflet tiles?

Update 2024-02-4: Opening the inspector tool in the browser, there were errors The resource at “https://<street map tile>.png” was blocked due to its Cross-Origin-Resource-Policy header (or lack thereof). I then found this GitHub issue and included the following

Cross-Origin-Embedder-Policy: require-corp
Cross-Origin-Resource-Policy: cross-origin

to the HTML header -- still no success. I am not familiar with HTML or web-dev so any further guidance would be much appreciated. The issue on GitHub is still open and sounds like the developers are also thinking about this.