Sous vide mode only works at temperatures no higher than 212F/100C, steam must be turned on. More information about it can be found here Sous Vide Mode
Please press the temperature mode button until you see the words sous vide appear to the right of it. From there you will be able to set the steam and temperature levels.
Setting through the app:
Please head to the bottom tabs and select the Oven tab. From there you’ll be able to turn on Sous Vide Mode with your desired temperature and steam levels.