Hello I am having a problem og banding on lens flares, feathers , gradients ecc...
I never had it before so I was wondering how it comes with Ae 2017 this is happening.
Banding is caused by limited color space. Change your project to 16 or 32 bit to eliminate banding. Your display may not be able to display smooth colors but when the project is 16 or 32 bit and you render to a 10 bit or better format for your production master you'll go a long way to removing the banding. If you render to a highly compressed delivery format like h.264 you will re-introduce banding unless you add some noise to the effect to hide it.