Let's presume I wish to save space on my PC by making a file online only. I
I'll show the steps.
1 - I create a brand new video file. This isn't a small file - 3Gb or so
2 - I move it into a Dropbox-linked directory
3 - It uploads and, at my broadband speed, this takes an hour or so
4 - Once it's fully uploaded, I right-click that file and choose "Online only". It goes grey for a few seconds so I assume it's now online only.
5 - A couple of seconds later, I get a message that the file is "Downloading". Indeed as are many other files in that directory now.
6 - In time, my PC disk space shows 0 bytes left and that "Dropbox has stopped syncing. Please create more space by making files online only."
7 - Grrr