TRA (Tax return access) services are only available for 2017 and later years. So nothing from 2016 will appear in the Filed Tax Returns section. Also, 2019 is the first year that this service is offered to Free customers, so if you used TurboTax Online Free in 2017 or 2018 (and didn’t add Plus), then those will not appear either. Furthermore, if you have multiple accounts, you will only see the returns for the account that you are logged into.
If you didn’t save copies of your previous years returns onto your own computer, you can still get the information that was contained in them from the CRA. You can do this through their My Account service.