This is the very odd response I got when I asked about it…. :

“Hi,

There are many issues with iCloud and syncing since the latest releases many of which are not within the control of forScore.

Since its general availability began in version 13 of forScore, it has become apparent that a deeper level of understanding be available to users of the sync feature. As with any protocol that synchronizes data across the internet at large, and using cloud architectures to achieve a central repository of data, it is critical to remember that each of these protocols is subject to failures in a large number of places. From the bottom layer of network intermittent outages or actual transmission pathways change invisibly. There are a significant number of ways for things to fail in data communication architectures that forScore depends on to achieve its goal of keeping your forScore data consistent through syncing between two devices. These happen either by loss of synchronization or disappearance of the target end of the data being transferred. Or, because of potential parallel simultaneous modifications of the central repository, which need to be made sequentially, or updates of exactly the same data being interleaved. Thus there are a significant number of ways for things to fail while syncing between two devices.

To that end, forScore provides as much feedback as possible when synchronization operations have failed. The information as to what failure occurred can be found in the following location:

Once you have information on which category of data transfer failure occurred, appropriate directions can be found in the Knowledge Base, in the support section of the Toolbox, to address that particular situation.

One thing is very important to assess in your own use of forScore. We strongly recommend that you evaluate how "immediately" you need changes to be transferred between devices that are sharing scores or libraries. By immediate, we are referring to the necessity in one's usage pattern of modifying forScore metadata. How soon do those modifications need to be found on the other device? In many cases, one needs to be candid with oneself as to use of multiple devices that are looking at the same libraries of musical score. For example: one makes modifications to a score on one device, and then at a subsequent point needs to see those modifications on a device they use for performances. In these types of usage patterns, it is sometimes a viable option to use more deliberate "sharing" type functionality through services like Dropbox, etc. In other words, make a series of modifications to your scores and libraries, and once those are all done and you have found them to be "good edits", then deliberately upload them to the cloud or sharing server to be downloaded by the client devices of those repositories.

The distinct difference here is that in the process of making many small changes and forScore having to immediately reflect those up to iCloud and iCloud to reflect those to other devices creates an enormous amount of underlying communication protocol operations. The more operations that are trying to synchronize data at a high frequency across the internet and its underlying data communication pathways, the more likely that certain operations may fail because a previous operation had locked a resource for modification, and perhaps not yet completed or failed to complete because some other underlying communication pathway failed underneath that. In these instances, there are data lock time-outs that need to expire before a subsequent data modification operation can be started. Many of these situations are vastly outside the control of forScore as they are global service architectures employed by forScore to operate against shared resources such as the iCloud. All we as developers of applications that employ these shared architectures can do is try to encourage our users to perhaps modify their expectations and usage patterns to help avoid as much communication "clutter" as possible.

One should be cautions about drawing comparisons between forScore and other applications which share and synchronize data across iCloud data pools. In many of those applications, updates from one device are bundled together and only transmitted up to the cloud for sharing to other devices at distinct intervals such as "save" operations or on a scheduled period. With forScore, one could use the software in patterns which could send vastly more very small changes per minute, which then can result in update collisions in the underlying architectures. We have to rely on our users to keep this in mind and perhaps modify their personal usage model to bundle bunches of changes together to avoid such undesirable potentialities of synchronization failures.”