App camera doesn't work after display replacement

I changed the screen in an authorized official samsung center as I had it completely split. After the screen change I was called from the center asking me precisely if the cameras do not work from the beginning but before the screen change they worked. They do not work only within the app camera or even a GCAM, however, if I use for example the camera of social networks such as Snapchat or Instagram they work. What may have happened?