I installed the update AND the ODST DLC, launched the game and of course, it said “ODST content is not installed”. Closed the game, checked what the MS Store said (“installed”), relaunched the game multiple times but it still said: “ODST not installed”.
Then I remembered that I had the same issue with the Halo 3 update and that a reboot fixed it for me.
So I restarted my pc and suddenly I have ~90 GB additonal space on my SSD. You wanna know why? Because the whole base game, Reach, CEA, H2A, 3 and ODST are just gone. Very cool.
Great work!