Please share your code and I'll take a look. Before that, do make sure your code uses the same partner ID as when you use test on https://developer.kaltura.com/console/#/playlist.list
If you connect your iOS device to a laptop and run a sniffer, you should be able to see the exact api_v3/index.php?service=playlist&action=list HTTP request being made to our endpoint, which should include the KS, that KS can also be decoded so you can see its attributes.