When processing drone imagery, our system defaults to using the CPU for generating an Orthomosaic in the Ortho Product Wizard despite adjusting the environment to a parallel processing factor of 100% and the Processor Type to GPU (we have two on our machine, so we set the correct image processing GPU to ID 0).
This has never been a problem for us before the most recent update. The GPU we have is a NVIDIA T1000, which should have high enough processing capabilities, and has successfully created orthomosaics in the past. The CPU has been able to process imagery, but it takes about 4 times as long as the GPU.
I ran into the same issue after the last update it seems the software sometimes stops detecting the GPU properly. Try reinstalling or updating your GPU game drivers and double-check the GPU ID in the settings. Also, make sure CUDA is enabled and compatible with the current version; that usually fixes the GPU fallback problem.