It wasn't Zen that updated your Fritzbox, but AVM. New updates are pushed automatically to all connected Fritzboxes unless you opt out. So, I'm afraid nothing to do with TR-069.
AVM are aware of the few bugs in the English translation. Plus, there is an issue with the display of not all clients properly displayed on the WiFi network. For example, my chromecast audio is connected but not listed in the list of online devices. Nevertheless, this is not consistent behaviour affecting Chromecast audio only.