On a recent trip I had around 600 balance when I entered Skyway SB so when I reentered SLEX from Eton a few hours later the balance shown was around 350+ as expected. When I exited at C5 it showed a balance of -50 but there where no alarms and the gate let us through. Double checking the app it really says -50 and the account is now deactivated. What gives?

Sent an inquiry via the app earlier today. No reply yet.