Dolby Vision or High Dynamic Range Not Working on Fire TV Smart TV

Check your cable connections and verify which video formats the content supports.

1. Check if the content supports Dolby Vision, 4K, or HDR.
2. If the content comes from a connected device:
   1. Connect the device with an HDMI cable.
   2. Restart the connected device.
   3. Set the source device to output Dolby Vision, 4K, or HDR.
   4. Go to Settings on your Fire TV Smart TV.
   5. Select Display & Audio, and then select Picture Settings.
   6. Select the HDMI input that your device connects to, and then select HDMI Input Mode.
   7. Change the input mode to Auto or Mode 2 (2.0).
3. Try to restart your Fire TV Smart TV:
   1. Go to Settings on your Fire TV Smart TV.
   2. Select My Fire TV or Device & Software.
   3. Select Restart.
4. Make sure that the app is up to date:
   1. Go to the Appstore and then search for the app.
   2. An option to update shows if there's an available update for the app.
5. Reset your Fire TV Smart TV:
   1. Go to Settings on your Fire TV Smart TV.
   2. Select My Fire TV or Device & Software.
   3. Select Reset to Factory Defaults.