If you have installed the SCCM agent of a recent Technical Preview Build on a client it is not possible to push the current branch agent to it. I tested this with TP 1706 / CB 1702 and with TP 1707 / CB 1706.
This does not work even if the options Always install the client and Uninstall existing Configuration Manager client before the client is installed are selected.
As you can see in the log the request is skipped because a newer agent version is already installed.
You have to manually uninstall the Technical Preview agent before pushing from the CB console