this event is always bugged, I used to submit bug reports for this but there doesn’t seem to be a point since it’s been bugged like this since the game launched.
the problem is snips from wiki
When Halt dredge expansion by defending Fridgardr Lodge fails, the event to recapture the lodge sometimes won’t ever start; blocking event progress.
This meta event frequently bugs and becomes stuck, blocking event progress. This can be identified by the meta event UI saying “The dredge and the Priory are competing for the center camps.” even when there are no active events at Fridgardr Lodge or Firebase Molek. When this occurs, [Group Event] Defeat the dredge commissar cannot start.
This should be a known problem, why has it been broken this long? at best this event lasts 4 to 5 days from a patch and remains bugged till the next patch.