Oldguy001,
Welcome back. I've changed your post subject to refer to your specific question and moved it to the Library Parts forum (although the solution is also Working in ARCHICAD content). Please use a specific subject and the closest forum subject that the questions seems to fit in ... but feel free to ask as many questions as you need as you get familiar with all of the changes since V11.
The display of the opening lines is a setting in Model View Options ... which you will see abbreviated as MVO in the forum. I'm not seeing the old checkmark in the USA AC 24 library MVO settings to turn the opening lines on and off in 2D (it is there for 3D). Probably my old eyes. But it is also possible that there is a pen color conflict with your black background - as the MVO can change the pen. You might also try changing your background color at least temporarily to see if the lines are there but just invisible with the black background. A good diagnostic color is a light even color that will allow both white and black to be seen... white and black backgrounds make it hard to visualize white/black lines and fills.
Cheers,
Karl
One of the forum moderators
AC 28 USA and earlier • macOS Sonoma 14.7.1, MacBook Pro M2 Max 12CPU/30GPU cores, 32GB