After the last changes to the aircraft carriers that gives them a separate module for building units the two Seraphim aircraft carriers count towards the objective (I saw the objective marker "following" them), but even if I destroy them the progress is not counted. After destroying the entire Naval base the objective was at 12/14, and having no remaining units/building on the objective area the game is basically soft-locked.
Red Flag mission is soft-locked
https://github.com/FAForever/fa/pull/5610
Jip made a fix already, should be part of the next hotfix