I've noticed this happening a lot lately. Not all the critical missions will populate on the mission board. This means you have to manually go search for a Critical hive queen missions by jumping into all the roid sectors in all the hive systems. Usually it's only 1 Critical mission that doesnt show up per hive. It happens in Serco space, Grey Space, and Itani space. And it really sucks because with that queen still a live its impossible to do the the Leviathan.

ya i had this yesterday also, i got me first goliath then headed back to cantus systems, than bam no missions related to blue space beside deneb skirmishes, a few escorts and odia hive skirmishes. i waited i think 3 hours, but after the severs restarted then i got them while later.

Sacred star that is because the leviathan was killed and not what I'm referring to.

Usually if the life counter for the non-hive NPCs is low the mission stops showing up. Same thing happens for Deneb. There are others ways to find the missing queens than searching every roid sector.

The only other way I know is to follow the bots once you beat another hive mission. But this should still be fixed.