Hi! I'm experiencing this bug since I upgraded from Skype 7.x to Skype 8 for Desktop. From start I thought this bug is associated with Skype itself, but now I'm almost 100% sure this bug is related to Ccleaner.
So when I boot up Windows 10, Skype is starting automatically. From very start I can see Skype icon on notification bar. When I run Ccleaner, then after while (in most times when screensaver has started and then you move mouse again) Skype icon disappears from notification bar, but Skype keeps running normally. I have attached picture how it looks. This bug is active until I restart or shutdown and then power on PC. If I have not run Ccleaner, Skype icon on notification bar does not disappear.
There is no any option for Skype 8 for Desktop on Ccleaner settings. I have not tried exclude Skype folders from Program Files and AppData, but I thought this bug should be reported, so I did it.