Hello Dan,
I've tried on a smaller sample of just 17 polygon objects and with a smaller clipped raster and it got to 6% and stopped. I then tried on just one object with even a smaller clip of the 3DEP raster and got the following:
Is this tool being deprecated? Esri explanation doesn't say on the matter. I guess I'll contact them on the matter.
My system info is intel i7-9850H 6 core CPU, 32GB RAM, Nvidia Quadro T2000 and Intel UHD Graphics 630