Quickfix Azure function: local.settings.json not working
Here is another post for future me. What to do if your local.settings.json file in your function app are being ignored

I was struggling with my settings when trying to run my function app on my local computer. I was using Visual Studio and my function app had a local.settings.json file with some settings in it. But for some reason these settings were ignored.
Copy the local.settings.json file to the output directory
In your csproj file add this line:
<None Update="local.settings.json">
<CopyToOutputDirectory>Always</CopyToOutputDirectory>
<CopyToPublishDirectory>Never</CopyToPublishDirectory>
</None>
You can also use the visual editor in Visual Studio. In the properties tab of your local.settings.json file make sure the Copy to Output Directory is set to copy always.

This will make sure the local.settings.json file gets copied to the output folder and will be picked up by your function app.
Remember that you must rebuild your project if you make any changes to the settings.
If you are encountering the same issue, I hope this method fixes it for you.