Updated for OnApp 5.2 (7th December 2016)
This issue has been resolved in version 5.2
In OnApp versions 5.1 and before, there was a known bug where the automatically generated password is not updated inside of the OnApp UI.
For previous OnApp versions, the workaround for this is to resync OnApp with your vCloud Director instance manually. Please read this document to perform this or submit a ticket to our support team.