A colleague of mine today had a problem with plotting, all plots came out with a singlular line thickness. First I thought, that will be no plot style being used? Not the answer. Then I thought, all layers set to a really thin line? Also not the answer.
Then it occurred to me! Is it actually plotting the line weights. The answer was no, that box was unchecked! Though you couldn’t check it again as it was greyed out. Huh?
The answer is as follows:
Type PLOT (or CTRL-P, etc), uncheck Plot with Plotstyles, check Plot with line weights, check Plot with plot styles again! Now you will be able to plot with line weights again!
This behaviour does however seem to be fixed in AutoCAD 2013 and line weights and plot styles can be individually checked! Thank you Autodesk!