No output (unknown) from Lambda function

Hi, Im getting an UNKNOWN output from my lambda function


- platform: template
    name: "solar bed rotation"
    id: solar_bed_rotation
    update_interval: 1s
    
    filters:
     - lambda: |-
        return  (atan2(id(mpu6050_accel_x).state , id(mpu6050_accel_y).state)*180.0) / 3.14159265359;
     - heartbeat: 1s

In Home Assistant front end I just get State “UnKnown”

Full code as follows:

esphome:
  name: solar_tracker
  platform: ESP32
  board: esp-wrover-kit


wifi:
  ssid: "####"
  password: "####"
    # Optional manual IP
  manual_ip:
    static_ip: 192.168.1.156
    gateway: 192.168.1.2
    subnet: 255.255.255.0


  # Enable fallback hotspot (captive portal) in case wifi connection fails
  ap:
    ssid: "Solar Tracker Fallback Hotspot"
    password: "lZEGI44isCwX"

captive_portal:

# Enable logging
logger:

# Enable Home Assistant API
api:

ota:

i2c:
  sda: 21
  scl: 22
  scan: True
  
sun:
  latitude: ####°
  longitude: ####°

time:
  - platform: homeassistant  
  


button:
  - platform: restart
    name: "solar tracker Restart"


sensor:
  - platform: sun
    name: Sun Elevation Max
    id: sun_elevation_max
    type: elevation
    filters:
     - max:
        window_size: 1440
        send_every: 1
        send_first_at: 1
  - platform: sun
    name: Sun Elevation
    id: sun_elevation
    type: elevation
  - platform: sun
    name: Sun Azimuth
    id: sun_azimuth
    type: azimuth
    



    
    
    
#  - platform: template
#    name: "Bed Azimuth"
#    type: float
#    lambda: return  (atan(sensor.mpu6050_accel_y / sqrt(pow(sensor.mpu6050_accel_x, 2) + pow(sensor.mpu6050_accel_z, 2))) * 180 / PI);
#    lambda: return  (atan(mpu6050_accel_y / sqrt(pow(mpu6050_accel_x * 2.0) + pow(mpu6050_accel_z * 2.0))) * 180.0 / PI);
#    lambda: return  (atan(mpu6050_accel_y / sqrt(pow(mpu6050_accel_x * 2.0) + powmpu6050_accel_z * 2.0))) * 180.0 / PI);
    
  - platform: mpu6050
    address: 0x68
    update_interval: 1s
    
    accel_x:
      name: "MPU6050 Accel X"
      id: mpu6050_accel_x
      unit_of_measurement: "°"
      filters:
       - sliding_window_moving_average:
          window_size: 10
          send_every: 1 
       #- calibrate_linear:
          # Map 0.0 (from sensor) to 0.0 (true value)
          #temp change to max min until full.calibration full east raw -7.44 with direction 72 . west raw +8.86 with direction 250
          #- -7.44 -> 80 
          #- 8.86 -> 250
           
 #########################################       
      # - lambda: return  {(atan(sensor.mpu6050_accel_y / sqrt(pow(sensor.mpu6050_accel_x, 2) + pow(sensor.mpu6050_accel_z, 2))) * 180 / PI)};
         # accAngleX = (atan(AccY / sqrt(pow(AccX, 2) + pow(AccZ, 2))) * 180 / PI)
    accel_y:
      name: "MPU6050 Accel Y"
      id: mpu6050_accel_y
      unit_of_measurement: "°"
      filters:
       - sliding_window_moving_average:
          window_size: 3
          send_every: 1
      ##sensor was reading from 0 to 5
#       - multiply: 2
       - calibrate_linear:
          # Map 0.0 (from sensor) to 0.0 (true value) max down angle measued at 29 with raw sensor reading 8.9
          - 0.0 -> 90.0
          - 8.9 -> 29   
          
          
    accel_z:
      name: "MPU6050 Accel z"
      id: mpu6050_accel_z
      unit_of_measurement: "°"
      filters:
       - sliding_window_moving_average:
          window_size: 10
          send_every: 1 
    gyro_x:
      name: "MPU6050 Gyro X"
      filters:
       - sliding_window_moving_average:
          window_size: 10
          send_every: 5 
    gyro_y:
      name: "MPU6050 Gyro Y"
      filters:
       - sliding_window_moving_average:
          window_size: 10
          send_every: 5 
    gyro_z:
      name: "MPU6050 Gyro z"
      filters:
       - sliding_window_moving_average:
          window_size: 10
          send_every: 5 
    temperature:
      name: "MPU6050 Temperature"
      filters:
       - sliding_window_moving_average:
          window_size: 10
          send_every: 5 
          


  - platform: template
    name: "solar bed rotation"
    id: solar_bed_rotation
    update_interval: 5s
    
    filters:
    # return (id(mpu6050_accel_x).state +100.0);  ###test
     - lambda: |-
         return  (atan2(id(mpu6050_accel_x).state , id(mpu6050_accel_y).state)*180.0) / 3.14159265359;
        
     


cover:
  - platform: time_based
    name: "East West Solar"
#1.66min is 1 min and 40 sec
    open_action:
      - switch.turn_on: relayEast
    open_duration: 1.9min 
# open is move west
    close_action:
      - switch.turn_on: relayWest
    close_duration: 1.9min

    stop_action:
      - switch.turn_off: relayWest
      - switch.turn_off: relayEast

#relay bank Manual Switching
switch:
  - platform: gpio
    pin: 23
    id: relayUp
    name: "Solar Up"
    inverted: yes
    on_turn_on:
    - delay: 240s
    - switch.turn_off: relayUp
  

  - platform: gpio
    pin: 19
    id: relayDown
    name: "Solar Down"
    inverted: yes
    on_turn_on:
    - delay: 240s
    - switch.turn_off: relayDown
    
  - platform: gpio
    pin: 5
    id: relayEast
    name: "Solar East"
    inverted: yes
    on_turn_on:
     - delay: 240s
     - switch.turn_off: relayEast

  - platform: gpio
    pin: 17
    id: relayWest
    name: "Solar West"
    inverted: yes
    on_turn_on:
    - delay: 240s
    - switch.turn_off: relayWest

I am not sure, perhaps you need to include the library containing atan2?