If you have iCloud syncing problems, please, kindly make sure you log in your devices using the same iCloud account and have a stable Internet connection. Besides, make sure that you have the latest iOS version – the matter is that Apple made iCloud Drive mandatory with iOS 9 which means older versions (iOS 7 and lower) can’t be synced anymore.
If the problem persists, please, do the following:
1. Make a backup of your device with iTunes or iCloud.
You can find more detail on how you can restore or set up your iOS device from iCloud on the official Apple site:
2. Switch off iCloud in the app on all devices.
3. Go to the device with the up to date data and press “Delete iCloud data” under “Settings” > “iCloud/Dropbox” (with good Internet connection)
4. Wait 5 minutes.
5. Switch on iCloud on the device with up to date data and choose the “Upload settings” option.
6. Switch on iCloud on the other devices and choose the “Download settings” option.
This basically resets the syncing process.
Besides, we have added a Dropbox feature that enables syncing multiple devices and multiple iCloud accounts via Dropbox so you can try this sync method if you have issues with the iCloud sync.