You might have set your print to B/W in the Archicad pane of the Print dialog. I dunno if this is new default in AC11, but it's happened to me that I've got the wrong setting. If you set AC to print B/W all solid fills will print black. To get greyscale with that setting you need to use the percentage fills. They do not behave as solid, even iff they are not bitmapped as they were in earlier releases,.
If you, like me often use grey pens to get greyscale, you must turn
off
B/W in the Archicad pane of the Print dialog. This will print grey pens grey, but also colors will print in color. There is no greyscale print setting within Archicad.
If you want to turn all solid colors to grey when printing, you need to use a system or printer setting rather than Archicad's. On the mac you can use the ColorSync pane, and use the Quartz filter Gray Tone. Also, your printer might have options.
Below, examples:
First a screen dump. Then a scanned image of the printed result, first with Archicad's output with B/W off, then with it on.
AC4.1-AC26SWE; MacOS13.5.1; MP5,1+MBP16,1