After updating swashbuckle to version 5.0.0, some models have trouble serializing

**Description**
Using .net core 3.0 project, after updating swashbuckle library to version 5.0.0 some models have trouble serializing and swagger renders an error message upon clicking some routes.
In my case the error had problems with Enum and some classes.

**Expected behavior**
Models should be serialized.

**To Reproduce**
1. Open swagger
2. Click on route
