If sync stopped working, try the following steps, in order.
1. Check connection
Make sure you are indeed connected to the internet by visiting a website in your web browser.
Also, make sure you are logged into iCloud and iCloud Drive is turned on. For the Mac, you can see that in System Preferences. For iPhone, in the Settings app.
2. Wait a while
Most sync failures are temporary. If you just wait a few minutes to an hour, sync will resume by itself.
You can monitor the status of Savings’ sync by going to the iCloud tab inside Savings’ Preferences (Mac) or Settings (iPhone).
3. Turn Sync Off and On
If sync does not resume after after waiting a while, you can try turning iCloud sync off and on again on each of your devices. You do that by going to the iCloud tab inside Savings’ Preferences (Mac) or Settings (iPhone).
4. Reset iCloud Sync
In the rare case where turning sync off and on doesn’t work, you may have to reset the state of Savings’ iCloud data on Apple’s server.
- On each of your device, turn off iCloud sync.
- On one of your devices, go the Advanced tab in Savings’ Preferences (Mac) or Setting (iPhone) and click “Reset iCloud Data”.
- Turn on sync on one of your devices, wait for it to sync successfully, then enable sync on the remaining devices.
If you are still having trouble with sync after trying these steps, please contact support.