Issue with Exporting 3D Models from uMake to OBJ Format


I am facing an issue when exporting 3D models from uMake to the OBJ format.
I am using uMake on an iPad Pro. After designing a model in uMake, I tried to export it as an OBJ file. The export process completes without errors, but when I open the OBJ file in other 3D software e.g., Blender, SketchUp; some parts of the model appear distorted or missing.

The exported OBJ file should accurately represent the model as designed in uMake. But the exported OBJ file has missing elements.
I have referred Learn - Help - Export to File | uMake info for guidance but still need help .
Has anyone else experienced this problem?

Any help would be appreciated !

Thank you .

Best regards,