It may be that You will need to set up the lifx integration in the new app. In that case, click on the + in the upper right of the screen, choose Add Device, select by brand and find Lifx.
And when I mentioned the Classic app is being phased out… it is a slow process that has just started so don’t feel you have to be in a rush to perform this task. They are still working on the new app and it is not exactly finished at this point. At the very least, you should start using it so you can get familiar with it.