load multipart mesh in sprite3d

[kamranrad1993]

• cocos2d-x version: 3.14
• devices test on: pc(linux)
• developing environments
  • QTCreator

i create multi part mesh in blender and load it in a sprite3d.
when run the game nothing show in the scene ( just happened when using c3b or c3t files ) and sprite->getBoundingBox().size return (-199998,-199998) but when the mesh have one part sprite->getBoundingBox().size return true value.

(multi part mesh : for example 3 box that havent parent in the scene)
sorry for my english.