Web API with referenced to Managed Code 32bit

The Web API I'm creating links to Sage 300. When you reference the 2 DLLs that you need to connect to Sage's API, they are 32bit DLLs. If I set the project properties to be x86, running it loads the browser and then immediately exists with:

'dotnet.exe' (CoreCLR: DefaultDomain): Loaded 'C:\Program Files\dotnet\shared\Microsoft.NETCore.App\2.1.0\System.Private.CoreLib.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
The program '[14832] dotnet.exe' has exited with code -532462766 (0xe0434352).

If I set it to Any CPU I get:

System.BadImageFormatException: 'Could not load file or assembly 'ACCPAC.Advantage, Version=6.5.0.10, Culture=neutral, PublicKeyToken=4d7048ecf2312a7c'. An attempt was made to load a program with an incorrect format.'

Now I know this is because the Sage DLLs are 32bit. In Visual Studio 2017 there is this option:

 Tools
  -> Options
   -> Projects and Solutions
    -> Web Projects
     -> Uncheck "Use the 64 bit version of IIS Express for web sites and projects"`

It is unchecked. I checked it to see if it made a difference. It didn't. Any thoughts?