I don't see how the mode makes a difference. The client will check in and get the command that an upgrade package is there, but, it won't download right away. It goes through a check on its end to make sure it can accept it. When it checks in again, it will "accept" it, but, again, may not download it. It can check in once more before it downloads it and does the upgrade.
Did this work prior to 14 MP2?
If you install the package manually on the client, does it work?