I have recently upgraded from Archicad 15 and my coloured pen sets won't display the colour on screen. When i select from the pen type drop down list the colours are evident, however when i draw everything shows as grey. Any ideas?
Check renovation filters and status. Sounds like you may be drawing the lines on Existing status with a Proposed reno filter selected, or something like that.
Make sure the Renovation palette is on so you can tell easily.