I got fed up and rolled my iMac back from Sierra to El Capitan. I will wait until Chief Brains get around to upgrade the program.
Model Name: iMac Model Identifier: iMac17,1
Processor Name: Intel Core i7
Processor Speed: 4 GHz
Number of Processors: 1
Total Number of Cores: 4
L2 Cache (per Core): 256 KB
L3 Cache: 8 MB
Memory: 24 GB
Chipset Model: AMD Radeon R9 M395
Type: GPU
VRAM (Total): 2048 MB
Vendor: ATI (0x1002)