This happens occasionally in IRROPS situations...I've had a few occasions where a GA put me on a new flight when my first one was delayed or canceled, and those generally show up as "Method: Distance - Fare Unavailable" and also usually in the full Y fare bucket. That last part doesn't really matter as much anymore since Y no longer gets 1.5x EQM.

But note this isn't what the first posters in this thread are seeing. In the above situation it's a distance earning. They're seeing something that says exception, but the flight is crediting normally by fare paid. I've never seen that.