Specflow Project not reading app.config file

I recently migrated a .NET Framework 4.7.1 test framework to Specflow 3. The solution contained a MSTest Test project and clicking on a test in TestExplorer did not jump to the Feature file. Knowing it worked with a Specflow project I decided to convert it.

A Specflow project + MSTest was created and some test were moved. The stepAssemblies section in specflow.json was updated to point to the step definitions in the existing project (the aim is to have multiple test projects with only Feature files and sharing steps). The MSTest project use an app.config file to read in settings like BaseUrl in a BeforeScenario hook but it's not getting read by the new Specflow project.

Should the app.config file be somewhere else? Should I implement it in a different way like using a runsettings file for each project? Any suggestions appreciated, thanks!