We have been continuously testing, evaluating and working on iCloud sync over the past couple of years, but we still don’t offer an option to sync Notebooks with iCloud. Although iCloud has much improved, a couple of issues remain and keep us from activating iCloud sync in Notebooks. Here are a few details:
Notebooks needs a certain level of control over timing and sequence of synchronization. We need to make sure that certain files arrive in Notebooks before others, and some documents should not be synced at all. iCloud does not give us any control.
When syncing a huge number of folders and documents, iCloud sync tends to get stuck. This is not specific to Notebooks, it even happens when syncing a larger folder between two Macs via iCloud Drive, for example. This can quickly become a serious issue if you wanted to move a considerable number of documents to Notebooks through iCloud, as you may have to wait for a couple of hours until everything shows up. Moreover, you do not have any feedback about what is going on.
Even when sync has been set up, small changes can cause items to suddenly disappear from Notebooks or iCloud, and show up again a few moments or minutes later. This even happens with Contacts or Calendar, but it is not acceptable with documents or whole sets of documents.
These are the main reasons why we still do not offer sync with iCloud. We are not alone in this situation, as apps like Scrivener cannot use iCloud for similar reasons.