I am new to Fedora and KDE. I turn off switchable graphics and there is no problem. With switchable graphics enabled the login screen is blank. I guess when it comes up to enter the password to log in. I am using Fedora 29 KDE spin. I don't know what log files to include or where to find them. Though I am able to use the terminal I am not familiar with where the log files are and I am more used to GNOME and unsure about KDE which I am new to. I would really like help on fixing the login screen so I can see the login screen. It is blank when the computer boots up. The lock screen still works normally. It is just the login screen that is the problem.
Instead of mentioned bumblebee installation (working login screen is only a side effect of properly installed Nvidia proprietary driver), you can use negativo17.org guide (https://negativo17.org/nvidia-driver/). It will work just better.