Hi Jayanta
Thanks for your response!
Yes, this does work. However, the function I'm talking about here is a new one in Pro. As far as I understand, it creates a virtual raster in the project, rather than a fixed output. For that reason, it's much faster to process. It could also be incorporated into the new raster function workflows (which are similar to model builder).
This is more about reporting an possible bug in the new functionality, than seeking possible alternatives. I should have mentioned that to start with
Ben