GMail contacts did not make the move to new iPad

Bought my wife a new iPad. Did a full backup of the old, did the restore to the new. Most stuff seems to have transferred, but - her Contacts in her GMail accounts did not make the move to the new device. Discovered that the Contacts slide switch was/is not activated (green) in either iPad in Settings/Apps/Mail/Accounts. What do I need to do to make these transfer over? We still have both iPads. The backup and restore were done with my Windows laptop, not iCloud (long story).