I wrote a reply here yesterday, and it disappeared for some reason.
Have had the same problem for some time now, on many of the projects I'm working on. Are textures looking strange in your project as well? I find that as long as textures are blurry/broken up and those green lines don't match with the object, the model can't be exported to programs such as 3Ds Max or Sketchup.
What I've found is that some projects with terrain created with ArchiTerra 2 produce this bug, where the only solution is to delete the terrain and save the file. Sometimes saving to a module and importing to a new .pln works. Sometimes it's imported furniture that contains a bug, deleting it and saving fixes the problem. Sometimes it's stuff like railings etc.
Really hard to diagnose the problem, and it's making my job as an illustrator frustrating because I can't export any model sometimes.
Please give an update if you discover anything. 🙂