This is most likely due to Github changing what authentication methods are allowed to be used for 3rd party apps when connecting to a repository.
You will notice the following error produced when clicking the "Sync from repository" button:
error: "{"message":"Must specify access token via Authorization header. https://developer.github.com/changes/2020-02-10-deprecating-auth-through-query-param","documentation_url":"https://docs.github.com/v3/#oauth2-token-sent-in-a-header"}"
This will need to be fixed on the Devs end