a freind and i collaberate on projects and use dropbox to transfer files back and forth. he recentlytried a pro upgrade trial, but then got billed for 5 users for a year. he cancelled the pro status and reverted to basic. after reverting, he can no longer see my updates to our shared folder, and i cannot see his updates to it either. i tried removing him from the folder and resharing it. he accpeted the invite, i accepted the reply. but no joy. how do we resolve this?
The issue you have run into is because the changes to the shared folder is putting your friend overquota, so it cannot be synced to their account (and to yours as a consequence). What can be a temporary solution to that is that you share a link to the files instead (so as to grant the other user the ability to download files locally on his/ her device and edit). Then, they have to reupload the files to their own account and share a link with you as well. If their account is overquota, they will have to remove some files, in order to be able to do it.
Hope this helps. Please let me know if you need more details about it.