Icons on missing/being replaced on MacBook Air

Hello community!

I've been trying to find a solution for this but I haven't found a post where the person gets the same issue as me...
The thing is, the icons for some apps started to be replaced for a plain white sheet of paper with the "A" logo of the App Store (the one made with the pencil, ruler and brush). (Picture at the end of the post)

Right now what is missing is the icon for safari, earlier it was for Spotify, or WhatsApp desktop, or also League of Legends. The icon for safari is missing only on the doc, but it is visible in the Launchpad. However, another application that I just downloaded from the App Store (Lightshot, an app for taking screenshots) has its icon missing in the Launchpad.

I've had this issue with El Capitan, and now with latest version of High Sierra, the problem persists. I've also done a factory reset this week, but the issue is again there, it is not a big thing, but it is annoying, and I want my icons to be present and look good, since MacBook is pretty much about having everything looking nice and slick...