If your sources have disappeared, it's likely one of two reasons.
Your sources have expired. There are a couple reasons why this might happen, but you should have received an email from Synci with details from our open banking provider.
You have downgraded your subscription. If you used to be on the Advanced plan and had 3 bank connections set up, and then downgraded to Basic, the sources related to your oldest bank connection would be removed automatically. You should have received an email from Synci informing you of this.