Problem Phenomenon:
1. "Trouble syncing; waiting to try again"

2. "Sync is currently experiencing problems. It will be back shortly."
Causes:
1. Abnormal network status
2. Google-related components are not updated to the latest version.
3. Incorrect date and time settings
Solution:
1. Manually sync your Google Account
Open your phone’s Settings app.
Tap User & accounts > Google Account that you need to sync automatically > Enable Contacts.
If you have more than one account on your phone, tap the one you want to sync.
Tap More > Sync now.
If the Contacts of Google Account cannot sync automatically, please check your Network status, the update of Google and the update of the phone.
2. Remove and re-add your Google Account
3. Force sync your account
Option 1: Change date & time settings
Manually change the date and time so that both are wrong.
Go to Home page, then manually change the date and time so that both are right again.
Turn on Set time automatically and Set time zone automatically.
Option 2: Force sync using Phone app
Open your phone's Phone app.
Tap the Keypad
Dial
*#*#2432546#*#*You'll see a notification that says "Checkin succeeded." This message means your phone can sync.