I have a bulb Scheduled to turn ON at Sunset, OFF at Sunrise. The times it fired (as shown in History) only changed once in a week (at the beginning.) It’s now about five minutes out of sun-sync.
I have three Rules that are behaving similarly.
Has anyone else experienced this and found a fix? 
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Hmm. To start, I set the location in the app, with Android Location feature OFF - and that’s how I run.
I assume once a Schedule or Rule is saved with location in the app, it’s stored on the server. And sun-syncing takes place there?
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Must I have Android Location setting always ON for this feature to operate consistently??
(…later: Tried it. Made no difference.)
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I can’t get this to work. The app accepts the location and the Schedule or Rule and fires off ONCE correctly. But will not sun-sync incrementally. 