NOTE: Through continued use I've discovered that sometimes a FileProvider extension instance will remain running even after it has been unregistered from pluginkit. Thereforepluginkit -v -m -D -i my.bundle.id does not reveal its path. However One can still use pluginkit -r path-to-extension command to close the extension instance as long as they know the path.

Ah, my bad 🤦‍♂️ Then, not an expert, but my advice likely a signing/notarization issue: Does your FileProvider have an attached Sandbox capability? What kind of provisioning profile are you using? Developer or Distributed? Are your signing certificates still valid? Is you Main Application within the same App Group as your FileProvider? I personally found this thread to be quite helpful. Hope that helps.