And it looks like that was the problem. I have a glut of Navy commanders so it's not a problem there to fill all positions, but my army is a different story, half my rank 2 and up officers are lacking a Ground Forces Training Bonus, and so don't get assigned. Which is annoying, as that means none of my Division HQs and only half my Brigade HQs have a CO.
My army has been growing rather steadily, while my navy has mostly stuck to the same number of commands.
With that in mind, is it possible to get Task Force officers auto assigned? I have yet to see it happen.