Swagger UI showing .NET data types in Schemas section

I have Swagger UI implemented in 3 different .NET 5 projects. In 2 of the projects the Swagger UI page looks perfect and the Schema section shows only my objects (DTOs, my Enums, etc.). But one project is showing my stuff and also a bunch of .NET out-of-the-box objects like IContainer, CompareInfo, CultureInfo, etc. (prior to .NET 5 I would have called them Framework objects but that's not accurate terminology anymore). I'm not aware of any differences in the way I implemented the Swagger tools and I can't figure out why one project is showing extra schemas. Does anyone know of a setting or switch that maybe I have accidentally set? Thanks.