No problem now I know. Was the changed detailed anywhere? It does mean changing a fair bit of code, and would be a good idea to change the documentation perhaps.
These changes weren’t mentioned in Docs, but we will update it soon.
In conclusion, these parameters cannot be passed in the $$("uploader").send() method anymore, as there was an issue with sending them repeatedly after an unsuccessful request. On the other hand, formData property provides the stable performance.