Thanks for letting me know! I was able to replicate this issue after disabling all of my packs. It looks like, after the most recent game patch, including certain types of occult data in premade sim templates is causing issues on new save start if a mod user doesn't own the pack. This worked without any problems before.
If you currently own (but have disabled) the Vampires DLC, please re-enable it. I will remove this occult data from the next version of the mod. Special occult data will need to be in separate package files in the future.
Expect an update later today, this is an easy fix.