Leaflet not generating properly in dynamic R markdown document

Question

I have asked this question before here.

Initially the focus was on a point map, which the answer fixed. However looking at clustered and heatmaps, the issue persists.

1. Point generates fine (fixed via previous question)
2. Clustered do not appear on map
3. Heatmap doesn't show at all (whitespace)

Minimal code example:

library(tidyverse)
library(leaflet)
library(leaflet.extras)
leaflet()

long <- as.numeric(c("0.005638", "0.005648", "0.005658"))
lat <- as.numeric(c("51.62879", "51.62889", "51.62879"))
data1 <- data.frame(long, lat)


filtered_list <- 1:3
cat("## Tabs {.tabset .tabset-fade .tabset-pills}", "\n")
for (estates in filtered_list){
    cat("###", estates, "\n")
    cat("\n\n\n")
    cat("This is where the map will go ")
    
        cat("1 ")
# generate leaflet plot 
    page <- htmltools::tagList(
         leaflet() %>%
            addTiles() %>%  # Add default OpenStreetMap map tiles
            addMarkers(lng=data1$long, lat=data1$lat)
    )
    cat(as.character(page))

            cat("2 ")
    page1 <- htmltools::tagList(
         leaflet() %>%
            addTiles() %>%  # Add default OpenStreetMap map tiles
            addMarkers(lng=data1$long, lat=data1$lat, clusterOptions = markerClusterOptions())
    )
    cat(as.character(page1))



            cat("3 ")
    page2 <- htmltools::tagList(
         leaflet() %>%
            addTiles() %>%  # Add default OpenStreetMap map tiles
           addMarkers(lng=data1$long, lat=data1$lat) %>%
           addHeatmap(
    lng = data1$lat, lat = data1$long,
    blur = 20, max = 5, radius = 40
    )
    )
    cat(as.character(page2))
   
    
    }

The maps render fine in R Studio, e.g.