On new installs of the current release of UpdraftPlus, or old installs if you de-authorise and re-authorise the connection to your Dropbox, the Dropbox folder used to store your backups is now in the folder Apps / UpdraftPlus.Com. This is a change from the previous Apps / UpdraftPlus. If you want to learn more about this change, then please see this FAQ.

David Anderson (lead developer, UpdraftPlus)