Hmmm. I wish I could help.

I have one 2013 iMac on Catalina that won't run Big Sur and one 2011 iMac on Sierra, that won't go past High Sierra (which I tested on an external HDD). Mojave and beyond are right out because that iMac's AMD GPU doesn't support Metal, so it's a dead end except for running Poser 12 in Windows 10 under Parallels Desktop VM, which it does without a hiccough (Windows update issues aside ).

Those iMacs are still worthy windows machines, even if Poser 12 won't run on them natively. I read that M1 Macs also work really well as Windows machines with Virtual Machines. Lots of levels of code translation happening there, which they appear to be specifically optimised for.

Neither supports GPU Renders (too old, and the 2013 with NVidia GPU only has 1GB VRAM).

Apple need to hurry up and release their Apple Silicon 27" iMacs, which probably won't happen until late this year.

I do see that M1 Macs will support Octane X, so that's a pleasant prospect for future rendering.

I hear one of the P12 testers was using High Sierra until a few months ago, but is now on Catalina. I was hoping to get confirmation that P12 would run under Mojave, but it's still not worth it for me on the 2011 iMac as lack of Metal support will break macOS to the point of unusability, I hear.

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