Thank you for your inquiry. You may need to publish your channels if they are not showing up under the collection’s channel selection list. Collections only allow published channel selection to prevent some channels from showing up in Studio’s collections, but not on Kolibri (unpublished channels are not available to import into Kolibri). If you are still unable to access channels after publishing them, please let me know which channels you are trying to access, and I will look into them further. Hope this helps!