ExceptionReason() will only work within a Recover/Resume block. If you want to store ExceptionReason(), you can mark the current queue item as an exception and input the data there.
If you have no exception handling in your process, and the process dies mid-item, the item should be marked as an exception in the queue, but will likely have no detail. It is also likely that the item will remain locked, rather than being flipped to Exception status. Best practice is to always implement your own exception handling.
