I guess you've got Archicads print dialog setting to All Black. Because Archicad regards placed pdfs as not being transparent, but having a solid white background fill, that will print black as well.
One fix is to use some other way to get grayscale instead of black, such as the printer's own setting or some system setting. I don't know how to do that in Windows.
But the best way is to use a customized pen set for output, with all the pens you want set to black. This way you can also use colors for markup if you like. Note that you can choose a different pen set for drawing views on layouts than your ordinary working set, so this doesn't have to interfere with your working habits.
AC4.1-AC26SWE; MacOS13.5.1; MP5,1+MBP16,1