Dear Sirs, I really would like to use your software more often. But as I am traveling a lot using my iPad on my travels. The synching back and forth is just a nightmare. As the iCloudSync did get better over time now and as a lot of other programmers now offer iCloudSync with their also complex software, I am sure that could be done.
The problem with Dropbox is and always was security: I am not allowed to install it on my Mac.
So please look into Synching with iCloud,
Thanks
These comments about syncing haven’t changed recently, as far as I can tell:
I note that it says that Dropbox sync involves thousands of lines of code. 
Dropbox security is pretty much in line with every other cloud offering with possible exception of iCloud. I am aware that Apple don’t allow installation of any other cloud other than iCloud and one other who I guess managed to convince them their data could never be snooped on by internal staff to that company. Other companies may gave various restrictions based on their business case.
Im in communication with Alfons Schimdt, the developer of Notebooks.app, which I really like. He pointed me to the FAQ on the website until he finds time to answer directly. I read this, which I think is apposite to this thread:
Mark
Not having iCloud sync has definitely been one of my biggest complaint with this application. And even though I see that somebody has posted notes from another developer about all the reasons why they have not been able to use iCloud, I want to point out that that is an old post and Apple has made major improvements to iCloud and I see lots of other applications having had no problems syncing text whatsoever. For instants: MindNode, Notability, GoodReader, iA Writer, Ulysses, 1Password or another number of Apple apps (Pages, Notes, Numbers ). How is it all of this other applications are able to use iCloud sync with multiple files, but yours cannot?
The issue is not “multiple files,” as such. Rather, it is that the component files of a Scrivener project are all related to each other. So if, for example, you add a file to the project, the master index file used to build the Binder also changes. And if your iOS device gets version A of the Binder, but only version B reflects the new file, the file will appear to be “missing.” Panic and support emails will ensue.
None of the examples in your list faces this precise issue. In particular, note that Scrivener is not just “syncing text.” A Scrivener project can contain literally any type of file, including files that Scrivener itself cannot open.
In order to minimize the risk of this kind of problem, Scrivener requires much more control over the synchronization process than iCloud (or any other service besides Dropbox) offers. Until that changes, we will be unable to support synchronization via iCloud.
Katherine
This blog post (https://eclecticlight.co/2020/01/21/testing-icloud-using-cirrus/) by an experienced programmer and tech writer dates from January 2020 and has quite a bit to say about how unreliable iCloud is. Howard Oakley has even written a small utility (called Cirrus, which you can download for free) which can help to “unstick” iCloud when it stalls and fails to synchronise. As I have said elsewhere, if a programmer finds it worth his time to produce such a utility and make it publicly available, this suggests to me that iCloud is not working as it should. Something seems to have gone wrong back in October when Apple was about to roll out some improvements to iCloud and pulled them at the last moment. I have certainly found iCloud to be so slow and unreliable at times that I have moved most of my material to other cloud services. A few months back I was observing cases in which a text file of only a few kilobytes would sit for days without uploading. That was before I discovered Cirrus, which helps, but is not a solution to all problems.
All of that is independent of the fact that Scrivener’s project format is quite unlike the “flat” files used by programs like Ulysses, etc. If you want to see just how complex a Scrivener project is, in the Finder right click on the project’s icon and choose “show package contents” – but don’t mess with anything inside.
I’ve been using multiple macs while teaching online this quarter, and began experimenting with iCloud Files as a Dropbox replacement, since I’d just updated iCloud storage for photos and have a lot of excess capacity . Unfortunately there have been a few incidents where syncing didn’t happen for no identifiable reason and I’ve had to quickly copy files to Dropbox (and then go back after class and remove the duplicates…). iCloud is generally usable but I wouldn’t trust it with Scrivener sync at this point.
„get rid of dropbox“ (Edward Snowden).
Awhile back, I figured out how to sync from a Mac to iOS Scrivener and back. It’s a manual process involving a project in iCloud Drive, waiting for it to sync to iCloud (in the cloud), opening it in iOS Scrivener via the Files app, editing the project as needed, archiving from iOS Scrivener to a zip file, waiting for the zip file to sync to iCloud, then back to the Mac, unzipping the archive, and closing the loop with an updated project.
The problem isn’t only that it’s a manual process (that’s what you want Literature & Latte to fix).
In addition to that, a random time period was needed for the iCloud sync from Mac to iOS — an Apple process entirely. Dropbox doesn’t have that problem, or not as much at least.
Further to this, from forums on other products where iCloud is on offer (other than Apple’s products), or users using iCloud and sometimes brute force to do so, full of problems directed towards the products and not iCloud with the expectation that the product developers can coerce Apple to fix. I’d really not like this forum to turn into and fill up with “iCloud not working” reports which it probably will as iCloud doesn’t work as expected for many and there are no “knobs” to turn to make it work–even by the product developers.
I can see why iCloud-enabled products would be a nightmare to support. Dropbox gives very clear “here’s what’s syncing now” information. iCloud just does its thing quietly in the background, which is great until a file mysteriously fails to show up.