Error when generate isometric dwg ater using isometric stop sign

Hi Bentley,

There an error when i generate isometric dwg after i add the stop sign on 3D model. (refer photo)

So I delete this stop sign and then try generate iso again, but this error still appear.

I close 3d model file and open it again (3d model without stop sign), and try to generate iso, error still appear.

Final choice, I restart the PC and open the 3D file (without stop sign) again and generate iso, iso successfully generated.

This error appear because of this stop sign. How to fix it?

Thanks

HY