This might be the issue:

2020-09-20 15:48:38.831 WARNING: dzneuraymgr.cpp(307): Iray WARNING - module:category(IRAY:RENDER): 1.0 IRAY rend warn : GPU 1 (GeForce RTX 2080 Ti) with CUDA compute capability 7.5 cannot be used by iray photoreal. 2020-09-20 15:48:38.831 WARNING: dzneuraymgr.cpp(307): Iray WARNING - module:category(IRAY:RENDER): 1.0 IRAY rend warn : There is no CUDA-capable GPU available to the iray photoreal renderer.