Debug Blazor WASM projects with different StaticWebAssetBasePath - blazor-webassembly

Question

I had a working setup like this:
|_ Blazor WASM project 'A'
|_ Server project hosting 'A'
Now I added another Blazor WASM project (let's say 'B'). Each project can have a different life cycle/maintenance, their respective _framework folders will be shipped and hosted elsewhere (JS initializers will spin the components on a .NET framework site).
To that end, both projects have their StaticWebAssetBasePath property set (let's say 'A' and 'B') in their project file.
The site hosts both:
/A/_framework
/B/_framework
.. folders next to each other. This all works fine. However, I seem to have lost debugging capabilities. Breakpoints can be set but are never hit.
What changes do I need to do to make debugging work again?
Note, my Program.cs (server) has this:
app.UseWebAssemblyDebugging();
app.UseBlazorFrameworkFiles("/A");
app.UseBlazorFrameworkFiles("/B");
Method UseWebAssemblyDebuggin() has no parameters. Tried to create my own extension method but the original has internal classes which are not available to me. I also tried:
app.Map("/A', app => app.UseWebAssemblyDebugging());
... but some changes just make my browser stop.
Any thoughts or ideas?
Edit: I tried again, but this time from scratch: created a new Blazor WASM project (.NET6!) with a VS template. Debugging the Counter component works fine. If you then set the StaticWebAssetBasePath in the client project file ("Foo"). Next, change program.cs:
app.UseBlazorFrameworkFiles("/Foo");
Try with/without the following around the debug line:
app.Map("/Foo", app => app.UseWebAssemblyDebugging);
Try changing the inspectUri in launchSettings.json accordingly (with or without the /foo segment). Nothing works.