Yes, I’ve had similar issues when setting the temperature using the Bluetooth app. There seems to be some bug where the app sets the temperature in Celsius, even though the app and device are set for Fahrenheit. For example, if I’m cooking at 165F, the app will reset the device to 74F (the Celsius equivalent number, but in the Fahrenheit scale). It could be you’re having the same issue, but in reverse? You set the device for 120F, but it is resetting to 120C (above boiling and beyond the Anova’s rated limit!).
My issue seems to occur when the app loses its Bluetooth connection to the device and then reconnects. You can read more about it here: Timer Confusing or Broken?