If the drawing is set up to use CTB files, then it's possible that the assigned CTB file is setup to PRINT all ACI colors (those colors 1-255) as black.
Click the PLOT button, then in the PLOT dialog, look in the upper right corner under "Plot Style Table"
Is there something present? If it's "monochrome", then change it to None or maybe some other plot style that is not set up to change screen colors to black.
It's possible that the layout has a good color plot style assigned to it, but you don't have access to this file, or it's missing, etc. In that case, the dialog will look like this. (Note the yellow shield next to the plot style name)
You can also assign truecolors to layers and objects and they will print color regardless of the plot style chosen.