No map received warning when launching nav2 with rviz2 using custom robot simulation on gazebo – Ubuntu

System Specification

Ubuntu 22.04 LTS
ROS2-HUMBLE
Gazebo11

So basically, I am using gazebo to simulate an environment for my robot to map. Mapping using slam and nav2 works perfectly. However, when I want to launch the nav2 and rviz2 with the map that I had saved, the map does not load on rviz2
rviz visualization
The launch file is as follows:

import os
from launch import LaunchDescription
from launch.actions import DeclareLaunchArgument, IncludeLaunchDescription
from launch.substitutions import LaunchConfiguration, PathJoinSubstitution
from launch.launch_description_sources import PythonLaunchDescriptionSource
from launch.conditions import IfCondition
from launch_ros.substitutions import FindPackageShare
from launch_ros.actions import Node

MAP_NAME='playground' #change to the name of your own map here

def generate_launch_description():
    depth_sensor = os.getenv('LINOROBOT2_DEPTH_SENSOR', '')

    nav2_launch_path = PathJoinSubstitution(
        [FindPackageShare('nav2_bringup'), 'launch', 'bringup_launch.py']
    )

    rviz_config_path = PathJoinSubstitution(
        [FindPackageShare('linorobot2_navigation'), 'rviz', 'linorobot2_navigation.rviz']
    )

    default_map_path = PathJoinSubstitution(
        [FindPackageShare('linorobot2_navigation'), 'maps', f'{MAP_NAME}.yaml']
    )

    nav2_config_path = PathJoinSubstitution(
        [FindPackageShare('linorobot2_navigation'), 'config', 'navigation.yaml']
    )

    return LaunchDescription([
        DeclareLaunchArgument(
            name='sim', 
            default_value='false',
            description='Enable use_sime_time to true'
        ),

        DeclareLaunchArgument(
            name='rviz', 
            default_value='false',
            description='Run rviz'
        ),

       DeclareLaunchArgument(
            name='map', 
            default_value=default_map_path,
            description='Navigation map path'
        ),

        IncludeLaunchDescription(
            PythonLaunchDescriptionSource(nav2_launch_path),
            launch_arguments={
                'map': LaunchConfiguration("map"),
                'use_sim_time': LaunchConfiguration("sim"),
                'params_file': nav2_config_path
            }.items()
        ),

        Node(
            package='rviz2',
            executable='rviz2',
            name='rviz2',
            output='screen',
            arguments=['-d', rviz_config_path],
            condition=IfCondition(LaunchConfiguration("rviz")),
            parameters=[{'use_sim_time': LaunchConfiguration("sim")}]
        )
    ])

To reproduce the problem simply,

mkdir ws
cd ws
mkdir src
git clone -b humble https://github.com/linorobot/linorobot2 src/linorobot2
git clone https://github.com/linorobot/linorobot2_viz src/linorobot2_viz
rosdep update && rosdep install --from-path src --ignore-src -y 
colcon build

In one terminal run

source /opt/ros/humble/setup.bash
source install/setup.bash
ros2 launch linorobot2_gazebo gazebo.launch.py

Open another terminal

cd ws
source /opt/ros/humble/setup.bash
source install/setup.bash
ros2 launch linorobot2_navigation navigation.launch.py sim:=true rviz:=true

rviz will then show this
image
I have tried the nav2 turtlebot3 tutorial and their map shows up fine on rviz which indicates it’s neither a gazebo nor rviz2 issue. I checked our topic list and found /map, /map_server/transition_event, /map_updates are present.
I also cross-compared our launch file, robot_model file, and maps files with turtlebot3 but is unable to identify any part that is wrong. Does anyone have an idea about why the map is not received?