I have exactly , the same problem - and it can lead to data loss , if you duplicate a word doc for example , you can't rename the copy in Finder , but Word will let you do a save as to a new name and word is happy its been saved , but it hasn't the new name will show as 0 bytes, so if you delete the copy you have no version on disk.
Dropbox just seems to be badly broken on Macos now - GoogleDrive and MS OneDrive on the same machine have no such issues but they still support removable disks - the removal of that was when the problems started for me, so I'm migrating my files over to GoogleDrive and OneDrive and ending my dropbox subscription