SpiritWolf, this is a longshot since you say P8 is functioning correctly (and you've probably checked this already but I didn't see you mention it), but have you ensured your drivers are reasonably up-to-date? as OpenGL advances, older versions of graphics drivers no longer play nicely, and I do know that with P8, I needed to update my driver compared to the original Poser Pro.

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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