Causes of Gmail Not Syncing
A mobile app may stop syncing when some anomaly in data transfer generates a behind-the-scenes error that stops the app from working until the error clears. If the error cannot clear automatically, it appears to hang and won’t function as expected. Most transfer errors source to either unexpected glitches in network connectivity or timeouts related to the sending or receiving of large data chunks.
How to Fix Android Gmail Not Syncing
The most common cause of syncing problems with Gmail is between the main account and the Android app. Follow these steps to sync Gmail with your Android device:
How to Fix iOS or iPadOS Gmail Not Syncing
Syncing problems with the official Gmail application on iOS or iPadOS or with Gmail in the Mail app are a little different. Although some of the same troubleshooting steps for Android apply, a few fixes are specific to Apple devices. Open the Settings app. Tap Apps and Notifications or, on older versions of Android, tap Apps. Tap the Gmail app. Tap Storage & cache > Clear Storage, then confirm the action.