If that's not the case, please try these steps:
Close the Google Photos app and re-launch it.
Sign out and sign back in to Google Photos with the same Google Account.
Clear App data:
Open your device's Settings app (not the Google Settings app).
Touch Apps.
Select Google Photos in the list.
Touch Clear data.
Update the Google Photos app on your Android phone:
Visit the Google Play Store.
Open Google Photos.
Touch on Update.
Restart your device.