Recently, as in the past couple months, Soundcloud has stopped returning tracks for lots of artists using the API endpoint:
http://api.soundcloud.com/users/{USER_ID}/tracks?client_id={CLIENT_ID}
Why is this?
I am hoping for an answer to this by Soundcloud's support team, as I found the answer to SoundCloud API returning 0 tracks despite user having tracks unsatisfying.
You are probably getting a 403 error because the right holder disabled API access to the tracks. See this answer, hope that it is more satisfying.
SoundCloud emailed back saying they have introduced an option for right holders to disable all API access to tracks by default, returning this 403 error when requested. They also said it's understandable that this is a confusing feature, and that they hope to make it more clear.
And seems that you only get the 403 on specific tracks, but on the /tracks endpoint you just get an empty result, as I've tested for another question about this issue.