Issues with STI not staying loaded during development (rails 3.2.1)

Current setup:
Asset < AR
UserAsset < Asset
UserNote < UserAsset
UserDocument < UserAsset
UserSound < UserAsset
UserVideo < UserAsset

ProjectAsset < Asset

When I first start the server this is fine (I’ve got an initializer that loads them all), but after the first UserDocument create/save it loses the subclasses, like it’s dropping them from memory.

What would cause this?

I know this is pretty generic as far as questions go, but I think the problem is do I need to do more than have them loaded in an initializer during development?

Thanks for any help