Texture with alpha not rendering as expected on complex meshes

Observed when using full opaque png texture:

• Standard QT cube is rendered as expected
• Imported simple mesh (cube) is rendered as expected
• Imported complex mesh (car model with wheels) is rendered as expected

Observed when using semi opaque png texture:

• Standard QT cube is rendered as expected
• Imported simple mesh (cube) is rendered as expected
• Imported complex mesh (car model with wheels) is not rendered as expected

Notes:

• Only the black area around the text "working" should be transparent
• Same mesh and texture are working in other real time editors like Blender