Why iCloud tabs not working iOS 11 iPhone and iOS 10 iPad? Unable to see iCloud tabs on iPad (safari).

Tried signing out and in of iCloud on iPad. I can see iCloud tabs on iPhone from iPad.

iPhone on iOS 11 but iPad is too old to update from iOS 10. Does the feature not work if the devices are on different OS’s?
I’ve concluded that iCloud tabs don’t work on older OS’s (when other devices are on newer ones).