Hello Michael,
Note that not every processing task in Metashape supports GPU acceleration. The list of GPU-supported jobs are:
- image matching (first phase of Align Photos operation),
- build depth maps (first phase of dense cloud generation),
- build mesh (only when Depth Maps are selected as a source),
- refine mesh (can be called from Tools menu, usually not included to the common processing workflow).
If you are looking on the processing log, it is quite easy to see, whether the GPU is used. In the beginning of GPU supported stages you can see the initialization lines for the available graphic processing devices.