"You cannot add tracks to a playlist you don't own"

[thesillyoldbear]

We are using a heroku deployed app to Heroku (http://benchmark.co.uk/blog/slackbox-spotify-playlist-collaboration-through-slack/) and while it worked for a few days it now returns the message "You cannot add tracks to a playlist you don't own". I've checked values and keys in Heroku and the spotify developer portal, and everything is the same. What's going on?

[sillyoldbear]

Any help to be had here? I tried switching from the company account to my personal (which is premium) but after a few days of working it's throwing the same error.

[sillyoldbear]

And yes, I've also tried making it a collaborative playlist, but no deal.