Okay, I just tried it with default M4, and a quick glance suggests that M4 seems to export okay as you describe. But when I've got complex shaders in the scene, it apparently seems to throw Reality out of whack.

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Hardware: AMD Ryzen 9 3900X/MSI MAG570 Tomahawk X570/Zotac Geforce GTX 1650 Super 4GB/32GB OLOy RAM

Software: Windows 10 Professional/Poser Pro 11/Photoshop/Postworkshop 3