Whenever Cookie 5 is open on my Mojave 10.14.5 system (and earlier) I start losing my Favourites Icons in Safari. When I close Cookie 5 they come back. I am using the latest version of Cookie 5.
When Cookie 5 is running on Mojave 10.14.4 the icons of my favorits bookmarks in Safari disappear. When I quit Cookie 5 they return.