Incomplete infer for generic types

TypeScript Version: 4.0.5

Search Terms:
typescript, infer, incomplete, unknown, generic

Expected behavior:
The compiler should be able to extract information of the generic Item type from the function definition and infer string.

Actual behavior:
The compiler is able to infer the Names type as { id: string } but the Item type is unknown.

Related Issues:

Code

interface LoaderConfig<Key, Item> {
  loadItems: (keys: readonly Key[]) => Promise<readonly Item[]>;
  getKey: (item: Item) => Key;
  makeCacheKey: (key: Key) => string;
}

type LoaderConfigByName<Names, Item> = {
  [name in keyof Names]: LoaderConfig<Names[name], Item>;
};

function makeLoader<Names, Item>(
  configs: LoaderConfigByName<Names, Item>
): void {
  console.log(configs);
}

makeLoader({
  id: {
    loadItems: async (keys: readonly string[]): Promise<readonly string[]> => {
      return await Promise.resolve(keys);
    },
    getKey: (item: string): string => item,
    makeCacheKey: (key: string): string => {
      return key;
    }
  }
});

"use strict";
function makeLoader(configs) {
    console.log(configs);
}
makeLoader({
    id: {
        loadItems: async (keys) => {
            return await Promise.resolve(keys);
        },
        getKey: (item) => item,
        makeCacheKey: (key) => {
            return key;
        }
    }
});

{
  "compilerOptions": {
    "noImplicitAny": true,
    "strictNullChecks": true,
    "strictFunctionTypes": true,
    "strictPropertyInitialization": true,
    "strictBindCallApply": true,
    "noImplicitThis": true,
    "noImplicitReturns": true,
    "alwaysStrict": true,
    "esModuleInterop": true,
    "declaration": true,
    "experimentalDecorators": true,
    "emitDecoratorMetadata": true,
    "moduleResolution": 2,
    "target": "ES2017",
    "jsx": "React",
    "module": "ESNext"
  }
}

Playground Link: Provided

Start with the provided Playground link and the generic makeLoader example using TypeScript 4.0.5. Reproduce the inference result and trace the compiler's handling of the generic Item type. Done means the example infers Item as string while preserving the inferred Names type.