In case your contacts are in the Contacts app but hidden perhaps start
Contacts app > Settings > Default account for new contacts ← choose 
Contacts
Contacts app > Settings > Contacts to display ← choose All Contacts
To double check sync please try
- FP6 - synch options - where to find?
- Above you can check the time and date of last sync and also try “Sync now” where the name used is “Address books”.
- How does eDrive sync work?
Some in depth Contacts work: How to unify and sync Contacts + Webmail contact lists in /e/OS?
Other threads with hashtag contacts