24 just indicates an unresolved journey or money to pay. That is not a bug.
The only bugs so far are the lack of training of staff and uneducated
customers.

If you watch some of the customers at finchley central where the gates are
permanentely open. They will touch the exit sensor on the way in.
At present this will mean they only pay £1.60 for thier journey but in the
future it would probably be more like £3.70.

I also heard that Capping will be introduced in February. The testers are
out and about now to see if it is working.