I have 2TB of Dropbox for my Photo Albums (and have had for many years).
All folders were synchronised to my laptop but a mix of online and offline.
My laptop has circa 1TB free.
Last month Dropbox updated the Dropbox App and all files were removed from my PC.
I have added the Dropbox app back to my machine and there is not room to add all of my files.
Using selective sync I can add files to my HDD but when I set them to online only to free up disc space they continue to exist on my HDD. The white tick on solid green background turns to a green tick on white background (like they are online only) but they are still on my HDD.
If I use the 'Manage ****** drive space' the app will allow me to select the files and allow me to make them online only. The dark blue area of the used space bar reduces and I get the message; "All offline files were successfully moved to online-only, Nice!" But no ****** drive space is freed.
If you run 'Manage ****** drive space' again the offline files are all back.
You can make them offline repeatedly but when checking they are still there - even though the icon is green tick on white background (so they should be online).
If you go into airplane mode the online only files are still on my HDD.
I know I am not the only person having this problem. I have seen lots of people with similar problems and I cannot see any satisfactory explanation / solution.