Button passed to nested module doesn't work properly

For some reason I need to nest modules. I passed button to nested module mod_coordinates_server but when I click the button points do not show up on the map. I used here reactive and button is passed correctly - when you uncomment print(btn()) you'll see that values are returned to console upon clicking the button. It means that button works corectly. So why it doesn't work for points? Is it something wrong with the namespace?

Working example below:

library(shiny)
library(mapboxer)
library(dplyr)
library(sf)


moduleServer <- function(id, module) {
    callModule(module, id)
}

# UI #
mod_btn_UI <- function(id) {
    
    ns <- NS(id)
    tagList(
        actionButton(ns("btn"), "Click me!"),
        mod_coordinates_UI(ns("proxyMap"))
    )
}

# Server #
mod_btn_server <- function(id){
    moduleServer(id, function(input, output, session) {

        btn <- reactive({input$btn})
        mod_coordinates_server("proxyMap", btn)
        
    })
}


# Module Coordinates

mod_coordinates_UI <- function(id) {
    
    ns <- NS(id)
    tagList(
        mapboxerOutput(ns("map"))
    )
}


mod_coordinates_server <- function(id, btn){
    moduleServer(id, function(input, output, session) {
        
        ns <- NS(id)
        
        coords <- quakes %>%
            sf::st_as_sf(coords = c("long","lat"), crs = 4326)
        
        output$map <- mapboxer::renderMapboxer({
            mapboxer::mapboxer(
                style = mapboxer::basemaps$Mapbox$light_v10,
                center = c(174.387636,-33.543557),
                pitch = 5,
                padding = 0,
                zoom = 3)
        })
        
        observeEvent(btn(), {
            # print(btn())
            mapboxer::mapboxer_proxy(ns("map")) %>%
                mapboxer::add_circle_layer(
                    id = "xyz",
                    source = mapboxer::as_mapbox_source(coords),
                    circle_color = "#952444",
                    circle_opacity = 0.7,
                    circle_radius = 6
                ) %>%
                mapboxer::update_mapboxer()
        })        
       
    })
 }


# FINAL App #

ui <- fluidPage(
    
    tagList(
        mod_btn_UI("test-btn"))
)

server <- function(input, output, session) {
    
    mod_btn_server("test-btn")
    
}

shinyApp(ui = ui, server = server)

This has been answered in SO [here]( r - Button passed to nested module doesn't work properly - Stack Overflow)