If you're using a Newsify account, try restarting your device first.
If that doesn't help, you can try creating a new Newsify account using the Account setting (you'll need to do this if you deleted Newsify's iCloud data using the device settings). In the app settings, select Account at the top (you'll have to wait a couple of minutes until you get the Sync Failed popup or this will be disabled). Then select Add Account... and then Newsify account type.
Also, if Newsify completes syncing but changes to read items or subscriptions aren't reflected, you can also try turning iCloud Drive or iCloud Documents & Data off and back on again in the device settings under iCloud.