encryptPassword not working for backup

I am running

msdeploy.exe -verb:sync -source:backupManager=manifest.xml -dest:backupManager=TheWebsiteName,encryptPassword="PASSWORD"

But when I do i get

Error: The property 'password' located at '/appPoolConfig[@appPool=AppPoolName']/add[@name='AppPoolName']/processModel' is marked as secure. You must specify an encryption password to archive this property.
Error count: 1.

If I do

msdeploy.exe -verb:sync -source:manifest=manifest.xml -dest:package=package.zip,encryptPassword="PASSWORD"

it works

Any ideas why its not working for backupManager destination?