Why is my available balance negative when I have money in Reserves?

Here's how it works. Your total balance includes both your available balance and your Reserves.

But your available balance is what gets used for spending.

If you make a purchase that’s more than what’s available, your available balance can go negative—even if you still have money set aside in Reserves. We don’t pull from your Reserves automatically. But this is fixable.

To fix it, you can:
Assign the transaction to a Reserve
Move money from a Reserve to your available balance, or
Add money to your account