I had this problem also.
Enabling the online repos during the install (ftp) fixed the issue.
During the install there were many long pauses - using CTRL_ALT_F1 and CTRL_ALT_F4 helped by showing things were happening in the background.
You can also run TOP in CTRL_ALT_F2 and see there is plenty going on even if the other 2 terminals show nothing happening.
When Returning to the GUI CTRL_ALT_F7 - you may need to move Your mouse about a bit to show it's actually there.
After the install, just before the POST INSTALL CONFIG, i was shown a massive list of fails - i ignored this and all was OK for the reboot.
My nVidia graphics driver appeared to be ignoring the xorg.conf, and i was stuck in a stupid low resolution. Forcing the resolution through my DVI in the MCC setup for Graphical server, and then using the SYSTEM SETTINGS to select the newly available max resolution fixed this.
Greetings from MG8