UPDATE FOR SATURDAY, JAN 6 at NOON:
No, this is not some real world version of the movie Groundhog Day. Yes, the launch of the Falcon 9 carrying the classified payload known as ZUMA has slipped again -- this time to between 8 and 10 pm EST on Sunday the 7th.
The slips have been for a variety of reasons, none serious. The worst result of the delays, at least for rocket watchers, is that the work at Complex 40 to launch the Falcon 9 seems to be delaying the debut of the Falcon Heavy from Kennedy Space Center.
It is still hoped by SpaceX to launch the Falcon Heavy by the end of the month, but the booster must pass several significant tests -- namely a static test fire of the 27 engines -- before it can be cleared to fly. That test is expected to take place a few days after the Falcon 9/ZUMA mission is launched.