After sending the Issue Report it was discovered that I had been using the wrong API endpoint. Somehow (I can’t remember why) I was using the “playlistItem” endpoint which doesn’t support “localizations”, and needed to shift to using the “playlists” endpoint instead.
Furthermore when using a combination of both “snippet” and “localization”, they should be within the same parameter but comma-separated, however, Postman doesn’t auto-convert the commas in the parameters to “%2C” and therefore would cause further trouble understanding the requests. Fixing these 2 steps, it now works as intended.
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