In Unreal, and more specifically the Character class, gravity is hard-coded to be in the negative-Z direction. This results in the assumption(I assume) that the player will always be right side up. You have two options:
- Try checking the Use Controller Roll(or similar) boolean in the Character Movement Component on your character. If you then hook up your roll input to an Add Controller Roll node in your character, that might give you the functionality you need.
- Or, you could create a custom Character class. Not really advised, there’s a lot of work that went into that class. However, it might be necessary.