If you can only see runs from one data source, it appears you’ve created two different accounts. I’m not sure if the two accounts can be combined. Post a message in the Support group and see what response you get.
Generally what you are supposed to do is create one account using the login credentials for one data source. Then, from within that account, you add the other data source to your single account. Then you’ll see all of your runs in one place.
Many of us who use Garmin devices have done just that. Garmin devices are relatively new to this site. If you had a Garmin, you cycled the data through Strava (in my case) or some other site. That data then was brought into CityStrides. However, once the direct connection to Garmin was created, many of us moved our connection to Garmin. Now my account has my data from both sources in one place.