There is a new feature delivered from Colossal Order: As default option, all Service Buildings will only spawn the vanilla vehicle associated with this building.

Solution:

You need to go to each Service Building, which should spawn the vehicle of your choice. Click to it.

Look to the lower right side and locate the dropdown list. Usually here is the Vanilla vehicle shown (e.g Vanilla Police car).

Now select "Random" from the dropdown.

Now AVO will tell the game again, what vehicle to spawn.

Read the Wiki for a detailed explanation.[github.com]