No artefact with your 2 files for me :)

The display artifacts shown in that jpg are intermittent. Their appearances depend upon where you place the mouse cursor in a viewport. Not all cursor locations produce the triangle. It's something to do with the v4 file (maybe a superfluous point in the definition of the largest shape), since the original (MoI) version doesn't show the problem. Something is confusing the renderer into thinking there is geometry to render.

Now for the odd thing I just discovered:

Delete any object from the model. Then click undo.

No more display artifact!!!

Unfortunately, after saving the model, then reloading it, the artifact is back.

Thanks for the additional information. I've got a couple of ideas, I'll try to dig into this some more to try and figure it out (probably just after I put out the next beta).

Is this a recurring problem that you have seen with different files too? Or does it seem to be something specific to the geometry of this file?

- Michael