The exception are the Habbiins boxcars: they come out in a plethora of liveries. But the rest- the Laaers autoracks, the Zacns and Uacns tank cars, all of them: no dice. Nothing but default, ever. This includes both my own liveries (stored locally) and CC subscriptions (loaded from the cloud). It seems that first Rush Hour and then CC have progressively suppressed the game engine's ability or willingness to generate alternate liveries.
I had this problem; I eliminated all the liveries I was subbed to, after checking that my own liveries were spawning I re-subbed to one livery after the other (checking they spawn after each subscription), and that has fixed it. I believe between the various rolling stock I have a total of 5 liveries spawning on DRA. 2 subscriptions and 3 locals.