In the latest LR mobile version I can take a picture with LR mobile without adding it to the iPhones camera roll. They get the filename APC_[number].jpg Those pictures sync to my laptop too, without being in a collection.
See the sync arrow indicator:
But how can I get them out of my LR mobile in the phone later? And why are they synced at all, although they are in not a single LR sync collection?!
I've edited and synced thousands of pictures between LR and LR mobile, but this whole syncing is still confusing.
OK, solved: this behaviour is due to Adobes changed sync strategy: Stopping the sync no longer removes the pictures form their servers. And to remove pictures from the sync we need to right-click and say "remove from all synced photographs"