New Accounts Not Using Default OWAMailboxPolicy

My clients have a policy where their users are not allowed to change their password via OWA.

So I've set the default Outlook Web App Policy to uncheck change password and set the owavirtualdirectory -changepasswordenabled to $false.

I then had to run a command to change the -OwaMailboxPolicy to "Default".  This works fine as our 5000+ users are now using the default policy.

The problem is that when we create a new user account and mailbox, the -OwaMailboxPolicy is blank, and it's not picking up the default policy.

InternalSmtpSettings                    :
OwaMailboxPolicy                        :
OWAEnabled                              : True
OWAforDevicesEnabled                    : True

I can manually change it after the account is created, but being that this client is a school district and their accounts are created on a regular basis, this isn't a good solution.

Does anyone know why a newly created mailbox doesn't automatically use the default "Outlook Web App Policy"?