Originally Posted by plunet

At a random guess...
Flight was rescheduled from 4.00 to 2.00.
Shortly thereafter, the flight was rescheduled from 2.00 to 4.30.

There are a number of processes that need to run in airline systems (in ludong in those of partner airlines) after a reschedule of a flight, some of these are linked to the reschedule process, others are asynchronous and run as batch processes periodically.
Typically these processes would typically catch up with a schedule change after a few days, although they can be manually expedited if the flight is less than a few days away.
There was probably some suboptimal ordering of the various processes needing to run after two schedule changes in rapid succession, and it's taken a few days for this to be unravelled and fixed up.