How to turn Gmail notifications back on after uninstalling Google Inbox? I already use the Android Gmail app. I installed Google Inbox and was receiving double notifications. Inbox offered to stop receiving Gmail app notifications. I agreed to this.

Then, I no longer wanted Google Inbox so I uninstalled it. Gmail notifications did not turn back on. I checked settings, apps, Gmail, notifications checkbox (yes), but still no Gmail notifications.
Settings - Accounts - select Google - make sure sync for Gmail is turned on.