Did you also migrated the Projectile blueprint? I don’t know if migrating a blueprint also export the blueprints references inside the blueprint scripting.
Try to open the blueprint, maybe it failed to compile it.
Try migrating the CharacterBlueprint. That should include at least all Mesh/Animation/Material Data. But i don’t know if the including Blueprints migrate too. But you will see that at the point where the Editor shows you what will be migrated.
This is technically a solution not an answer to your question.
I’m working on converting everything from Shooter Game into Blueprints for the alpha of our community project. Check it out and post in the forums if you’d like. I’m giving all the work away. You can download it from our git repository. We are organized under a nonprofit structure.
You are welcome to download the project and fork it as your own. Then you won’t have to worry about migrating the shootergame character if you don’t want to.