hi! can you please share the package and blend file? it looks like there is no texture on the other side of the mesh. easy fix though. go into blender and select the parts where you're having transparency issues in edit mode. then do shift + d to clone it and then exit out of the action. then on the left side bar, going to shading/uvs and click flip direction. pop it in game and then see if you have any more issues.
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