There’s no reason you can’t use both Dropbox and iCloud to sync your files, but, as the folks at Dropbox explain, using both may lead to more issues like these.

Learn how to fix Dropbox deleting files automatically - Restore Files from the Deleted Files folder, enable Sync on all devices and check if you're removed from the Shared folder.

Dropbox on my Mac had been stuck for weeks trying to sync a file called main.scpt. Other files continued to sync properly in the background, so it wasn’t getting in my way, but it was annoying to see ...