Referencing enum inside of interface (API) project?

For a while now, I've been working on two projects in a solution. AppName and AppName.API. API stores all my interfaces, while AppName stores everything else related to the solution.

I've reached a stage in my project where I'm not sure what I can do here. I need to reference an enum from AppName in a class in AppName but the class has an interface from AppName.API

This means that AppName.API has to have access to this enum. If I can't reference AppName in AppName.API what am I supposed to do?

Some suggested AppName.Common, but that also references AppName.API already so I can't reference that inside the API project. Do I really have to make an AppName.Enums