What happened to this phenomenon

[treasureMoment]

i use OBJLoader and MTLLoader
This is the normal display

This is an error display

what happened？Unbelievable
Other models adopted ExtrudeBufferGeometry EdgesGeometry LineSegments
Please ！

add one ExtrudeBufferGeometry shows normal
Analyze the possible causes of errors
Simple fiddle can’t be reproduced

[donmccurdy]

Please provide more detail if you want help. We can’t guess what’s wrong from screenshots. Share code, the models, or a live demo.