1.0.0 Swagger UI empty when not debugging

When running the function app via func start or deploying via Azure devops, the swagger ui says No operations defined in spec

Steps to reproduce the behavior:
Create a new function app solution
- Choose Http trigger with OpenAPI
Update the OpenApi version to 1.0.0 ​
Debug the solution in Visual Studio 2019
Navigate to swagger ui, observe the spec for the default function
Stop running debug
Ctrl+` to get to Developer Powershell
type func start
Navigate to swagger ui, observe No operations defined in spec
​
I would expect the swagger.json to be generated via either method

Start by reproducing the difference between Visual Studio debugging and `func start` using a new HTTP-triggered OpenAPI function app and OpenAPI 1.0.0. Compare the Swagger UI and generated `swagger.json` in both modes, then identify why the deployed or locally started app exposes no operations. Done means the default function appears in the Swagger specification outside the debugger as well.

Written by the indexing model from the issue text.