files not uploading to iCloud
I see that this same problem has been posted for several months. This is STILL a problem... using Safari on my Mac Pro, trying to upload a spreadsheet to iCloud and continually getting a message that the file could not be uploaded, and try again later. There has been plenty of time for Apple to address this.
If I open the spreadsheet on my iPad or iPhone and then save to iCloud, it works fine. I can then download it onto my Mac, or iPhone, or iPad and make changes, which are recorded into the spreadsheet, and the modifications can be read and edited by all my devices. So the problem seems to be restricted to uploading the original file from the Mac to iCloud.
Emailing the spreadsheet to myself and opening it on an iOS device is a viable workaround, but that should not be necessary after investing a considerable amount of money in a powerful computer that is supposed to be integrated seamlessly into Apple's working environment.
Mac Pro