Is the sync working? Is it synced and up to date? Does this happen on all Collections, or just one?
Sign-in to Lightroom with a browser at lightroom.adobe.com. If the Collection successfully synced to the cloud you will see it here as an Album. You can create a public link from the Lightroom website, or with Lightroom on a mobile device.
This is a workaround for the Lightroom Classic issue. It's hard to say what exactly is causing the problem with the Classic Collection.
It works and then has a sync error and won't work. It is only in creating new collections in the cloud. Previous albums are fine. We can clear the faulty syncs and get it to work for a short time before there is another error. I am working with tech support.