So. I figured out the problem.
You can't put the mod on a version of Strive installed on a hard drive that has admin permission required to make changes. (This is often the default for C drive.)
I recently moved Strive to C, (which is my SSD) for faster loading. However, windows was giving me shit, asking for permission for everything, and being unable to make shortcuts for some insipid reason. Checking the debug log, I saw the mod kept trying to make folders on the C drive, but failing. So, I tried moving the modded-strive back to my normal drive, and now the mod works again.
TLDR; mod only works if admin permission is granted by default.