Awesome library, I use it in ayu (https://github.com/Zaloog/ayu) to watch for changes in test files, to automatically rerun those tests.
There are some big caveats to this approach. Note “Known Problems” for the library. Particularly, you need to use a polling backend for network / VM filesystems. I didn’t see any notes for the Python library and the fact that notify is still telling you this makes me suspect it will just fail to work in those cases.
There is also watchexec[1]. I like the fact that is it shipped as a sinle binary, so it's pretty easy to distribute [1]https://github.com/watchexec/watchexec