I got report back from Support and it's very discouraging:

Thank you for contacting Support. Poser Pro 2012 is not supported on Windows 8 or 8.1

If you have the SR 3.1 installed and you are using the External AIR Library, Poser Pro 2012 should work on Windows 8.1, but this is not a supported Operating System.

It worked fine for me in W8 proper.  Maybe it's a means to force me to get Poser 9 (2014).

A real bummer.

____________________________________________________________________________________________________________________________

Asus N50-600 - Intel Core i5-8400 CPU @ 2.80GHz · Windows 10 Home/11 upgrade 64-bit · 16GB DDR4 RAM · 1TB SSD and 1TB HDD; Graphics: NVIDIA Geforce GTX 1060 - 6GB GDDR5 VRAM; Software: Poser Pro 11x