I tried compiling the demo that came with the module using V3.12 and both characters in it had shadows. Are you sure that you didn't do any other things that may interfere with it.
If you cannot figure this out, you may upload your game source (containing just one room with more than 1 characters in it and has this problem is okay) and maybe some people would be able to tell you what's being wrong after looking at it.
If you cannot figure this out, you may upload your game source (containing just one room with more than 1 characters in it and has this problem is okay) and maybe some people would be able to tell you what's being wrong after looking at it.