This problem still exists!! I just lost very important data due to this issue! So frustrated. This problem should have been fixed by now! It was addressed in February and is still around. Also, i can't seem to find any previous version of PDF on the cloud to at least restore something.
The problem occurs when you open app and the file is already opened, opened with the older version. Also if you're not connected to internet and file is already opened, when it opens it still has the older version and would overwrite the new one once closed.
You are probably testing it with the file being properly closed in the app.