'rootDir' is expected to contain all source files; Angular Library 10; Multiple Entry Points Error;

I'm trying to implement multiple entry points in to my angular library(similar to material library) & getting multiple errors.

Environment

Angular  - 10.2.x
TypeScript - 3.9.x
ng-packagr - 10.1.x

Library structure is as below

@MyLib
├── src
    |-----Button
          ├──── ng-package.json
          ├──── public_api.ts
          |──── *.ts

    |-----Card
          ├──── ng-package.json
          ├──── public_api.ts
          |──── *.ts

    |-----Icon
          ├──── ng-package.json
          ├──── public_api.ts
          |──── *.ts

├── ng-package.json
|── package.json

When tried to implement multiple entry points without any dependency of one component into another - I could able to succeed & use it in other projects.

But when tried using one module in to another (for example, if i want to use Button & Icon in Card component), I get the below error.

export * from "./icon.module";
                ~~~~~~~~~~~~~~~
/overall-project/projects/my-lib/icon/public-api.ts:6:15 - error TS6059: File '/overall-project/projects/my-lib/lib/core/utils.ts' is not under 'rootDir' '/overall-project/projects/my-lib/card/src'.

'rootDir' is expected to contain all source files.

But this is what exactly Angular Material does it here - https://github.com/angular/components/blob/master/src/material/button/button.ts#L23

In angular/material, button component imports methods from other module(core module) & also implements multiple entry points.

Wonder why doesn't it work for me, any ideas???

PS: Haven't defined 'rootDir' anywhere in the tsconfig.json