YNAB You Need A Budget

[Telejoke]

When I upgraded to YNAB 3, the program told me I have a huge negative balance in the buffer. It carries this amount over month to month. My "available balance" and my bank balance are close enough to make me think simply balancing the YNAB checkbook with the bank would work, but where did this balance come from? How to prevent it from happening again once I put in some amount that is not from an income source?