Have you just started a new camaign and you aren't seeing any Advent Angels?

Don't worry. It should take you a few missions before you start seeing the the Stunlancer model, and even more before seeing the Archon. Once the Trooper is released, you'll start seeing the Angels much sooner.

Certain users were experiencing CTDs with RuntimeReskinAPI enabled. Five had reported this, and the API has been patched accordingly. Be sure and download the API's latest version so that you can continue to enjoy RRA with less interruptions.
Many thanks to MaXISerg for pointing out the root cause!

Issue only affects players who first subscribed during release 2. New subscribers are not affected.

Fix: Delete
Documents\my games\XCOM2 War of the Chosen\XComGame\Config\XComAdventAngels_NullConfig

If it helps (or doesn’t), please ping me on Discord so I can confirm.
I have completely deprecated that file, so this no longer affects the current builds.