Sorry for my late response!
I reset the SMC and the PRAM. That did't work for me either. The trick that Learoydouglas suggested (killall -KILL SystemUIServer) did the job for my other icons but not for the CC icon, as I find out.
Finally I reinstalled the CC Suite but with no succes. It was mostly the that icon that was doing wrong.
In the meantime I had some problems with inDesign as well. There were GPU like glitches that even adobe helpdesk can't fix. Since i am on a iMac from mid 2011 my Mac has a NVIDIA (CUDA) card that is not supported anymore. I was running In in some trouble with some other graphic programs to and it felt like the same glitches as the icons.
So I decided to downgrade to High Sierra where the CUDA driver are still supported.
I am not sure if the driver was the problem, but all is well now! The icons are good again and all adobe programs are running smooth.
So that's it for now. Thank you guys for the help!