I am working on a macbook pro 2015 and have both macOS and bootcamp installed. I have also activated the Document and Desktop sync on iCloud settings.
So the problem is that I have created a powerpoint on macOS and did some of the work until slide A. Then for some reason I had to continue with it on the bootcamp. So I have the icloud sync app installed on my windows 10 bootcamp and have access to my iCloud files there. I opened the powerpoint from the Document folder inside iCloud and did the rest of slides until the end. Carefully saving the document step by step. Then I saved the files and sent them via email, and closed the powerpoint app and shut down the macbook.
The day after that, I turned on the macbook to macOS and tried opening the slides once again to check if everything is correct, and to my surprise, the document was reverted back to the point A that I had worked on macOS, and all the work that I had done on the bootcamp and carefully saved on iCloud was gone. More interestingly, when finished editing i had created a pdf file of the slides in the bootcamp previous day, and the pdf file is there and has all the slides in it and works fine.
Apparently the Documents and Download sync of iCloud prefers to delete the content of iCloud and replace it with the content present on the local storage's Document folder whenever a version conflict happens. (This conflict has happened in powerpoint file because there was two versions of it. one on local mac the other on iCloud, but it didnt have problem with the pdf file as there was only one on the cloud).
But this is wrong. It should be handled by updating the local stuff with the newest version available from the iCloud. I mean the update should be both ways. I might update my file on another computer! It should not be reverted back to what it previously was on mac's local storage. This is the whole point of having a cloud storage!!!!