Custom collections don't sync?

I made a custom collection on my tablet and expected it to also be available on my phone. However, when I open GL on my phone the custom collection is not there. For me this makes the feature not very valuable.

Are custom collections supposed to sync to the account like notes etc.?

Custom collections do not sync and never have. Don't know if that is in the roadmap for the future though.

I recently submitted this as a feature request. Got a reply saying it may be considered for the roadmap. Hopefully they introduce this, as there is no reason for custom collections not to sync.