I think for the work-around you will have to us the “Pause On Finished Image. check box instead and the go to the layer to move or scale. If you think you will have to upscale then also check the checkbox to “Use Smart Objects”. That way the initial scaling it does is non-destructive.
This looks to be a GPU display issue where Photoshop is not updating the display on your system while the plugin is actively running. In order to speed up processing, Adobe doesn’t refresh the screen while plugins are running but it should when it comes to the scale step. If you use the “Pause on finished image” then the plugin will be completely idle when it pauses so that will for sure work.
The bottom line is that I have no control over how the Photoshop screen refresh happens and apparently something has changed, at least for certain GPU configurations. I’ll need to test this on various systems but if it’s a global issue then I will just remove that checkbox and only leave the pause on finished image since I won’t be able to control it and I doubt Adobe will modify the behavior just for SPA.