使用user_playlist_add_tracks添加歌曲时遇Unsupported URL/URI错误求助

我正在测试FestivalPlaylistMaker项目，目标是通过艺术家列表生成播放列表。已确认凭据和重定向URI均有效，测试了1位、多位甚至20位艺术家（受Spotify限制最多100首歌）的场景，均出现相同错误。

启动应用时的日志如下：

adding  1WsHKAuN9vDthcmimdqqaY Your Mind
adding  34I6QYP9yREZnvVZvDIo1u Legend
adding  1kMObCQiYe5opqybH7ZNPD Rave - Remix
adding  2zDCZ8jY4kjuUZbVROHaZj Your Mind - Radio Edit
adding  0I7ggM44AhOpWIZCM02HtP In From The Night - Adam Beyer & Wehbba Remix
adding song  0
Adding song failed:
http status: 400, code:-1 - Unsupported URL / URI., reason: None
adding song  1
Adding song failed:
http status: 400, code:-1 - Unsupported URL / URI., reason: None
adding song  2
Adding song failed:
http status: 400, code:-1 - Unsupported URL / URI., reason: None
adding song  3
Adding song failed:
http status: 400, code:-1 - Unsupported URL / URI., reason: None
adding song  4
Adding song failed:
http status: 400, code:-1 - Unsupported URL / URI., reason: None
Playlist Complete!

歌曲ID已正确存入数组：

['1WsHKAuN9vDthcmimdqqaY', '34I6QYP9yREZnvVZvDIo1', '1kMObCQiYe5opqybH7ZNPD', '2zDCZ8jY4kjuUZbVROHaZj', '0I7ggM44AhOpWIZCM02HtP']

问题出在调用添加歌曲的方法时：

user_playlist_add_tracks(username, playlist_id, tracks[:1], position=None)

每次执行都会触发以下错误：

http status: 400, code:-1 - Unsupported URL / URI., reason: None

求各位提供解决思路，感谢帮助！

内容的提问来源于stack exchange，提问作者PetiteFlamme31