Does PowerCinema 4 display all scanned found with thumbnails during channel scanning?

No, Powercinema does not show all scanned channels at one time during channel scanning.  Instead, it displays one single TV channel thumbnail at the bottom left, and shows all channels in a list on the right column.

To see all the scanned channels with thumbnails, you will need to go into TV Preview. This function is available for analog TV and is partially available for DTV channels in some regions.