The is obviously an issue with the NF module of SF since the version 6224.
Formlerly, when you default setting was to select H265 version, if for a movie that codec was not available, SF used to switch automaticaaly to H264 one.
Now, it does not and fails (error 210).
When you select a movie to download, pay attention to line "resolution" in the Netflix Downloader window. If there is no resolution, it means the movie is not available in H265. Switch to H264.