I just recently got LWCAD but it seems I've broken it. All of the curves are displaying as straight lines. See the attached screenshots for the error:

Ma3rk over on the Lightwave forums clued me in. Guess its a known bug, removing and re-adding the plugins to modeler solved the issue.

Reload the LWCAD plugin manually on (Edit / Edit Plugins ) and shows Add Plugins or Scan Plugins and finally goo to LWCAD Plugin folder and reload, good luck...