Data recorded prior to 30 days from the present day cannot be synced to your Motion Connected account. When data is synced it will show in your Motion Connected account immediately.
The MC Link app shows a daily summary of your activity data for the last 30 days from your Apple Health App.
If you wish to manually sync data or do not have the Automatic Upload feature turned on you will have to touch each daily summary box on the main screen of the app to send that data to your Motion Connected account.
With the Automatic Upload feature turned on, when you open the MC Link app any daily summaries that are new or have changed since the last time you opened the app will automatically be pushed into your Motion Connected account.