Amazon has now found a solution and fixed the problem. 🙂
Everything is working again and 1.0.5 is available in Amazon Store!
If I go into the address book -> menu -> accounts, I see the “Sync” popup and “Auto-sync app data” is not ticked
If I go into DAVdroid using its own launcher icon and go to the settings page, under the Synchronization heading it says “Every 1440 minutes + immediately on local changes”
Is there any reason these different views don’t appear to be consistent?
The system-wide Sync setting is not related to app-specific sync settings. “Auto-sync app data” is a system-wide switch that will be disabled, for instance, in energy-saving mode.
However, when the Sync switch is on, DAVdroid requests syncs every 1440 minutes from the system (note that the system sync manager calls DAVdroid, not vice versa).