I'm noticing a lot of users have had this same exact issue dating back a few years but no solutions:
https://forums.cgsociety.org/t/conforming-geometry-onto-curved-surface-without-scripts/2056605
https://www.youtube.com/watch?v=FQd_jIYh7B8 (comment section full of people with same problem)
I've been troubleshooting but can't figure out what the difference is. In this example, I successfully got patchdeform to work when using a primitive cylinder (left) but when I extracted a surface (right), I get "Illegal Patch" error.
