I hope that some of you can make those automations work again with the next points:
1) turn on your location services AND most important 'significant locations'
2) make sure the time zone location service in privacy and security settings is turned on. (sunset and sun rise may differ from location to location, even when you stay in the same time zone)
3) Set date and time in 'General Settings' to automatic.
4) Delete and set up all time or sunset and rise related automations. Be sure to undo and redo some specific weekdays. It seems that during updates this informations has not been set up right. This may also happen when you switch to another iPhone of pod or AppleTV. (I think )
5 Open iCloud settings on all your devices and switch off the Home app from syncing.
6) Shut down all your devices and restart them.
7) Open iCloud settings again and switch syncing for the Home app on.
(And when by accident you have 'Home Controller app' installed because someone told you it was so useful, just delete that one. It may mess things up, don't instal it again.)
These points are only for those with automations not working. Siri not working has another reason is my believe. I don't give any guarantees ;-) But it will be nice to know if some of you get the automations to work again.
