Everything works fine when I create a droplet, but if I edit a droplet in the Preflight window, the droplet becomes corrupted. When I execute the droplet, I get an OS error "You can’t open the application <droplet name> because it may be damaged or incomplete."

I investigated via Show Package Contents in Finder, and found that the directory structure in modified droplets is different from the directory structure of a non-modified droplet – see attached screenshots.

I'm running the latest Acrobat (20.0) on macOS Mojave (10.14.6), and I also experienced the same problem a few months ago on High Sierra, before I upgraded to Mojave.