Typescript declaration files gets built in incorrect directory

I have three projects, **Project A**, **Project B**, and **Project C** that looks something like this:

## Project A
```
// package.json
{
"main": "build/index.js",
"module": "build/index.modern.js",
"types": "build/index.d.ts",
"source": "src/index.ts",
}
```
The project outputs the declaration file correctly inside `build/index.d.ts`
## Project B
```
// package.json
{
"main": "build/index.js",
"module": "build/index.modern.js",
"types": "build/index.d.ts",
"source": "src/index.ts",
"dependencies": {
"@my-workspace/project-a": "^1.0.0",
},
}
```
The project **INCORRECTLY** outputs the declaration file inside `build/project-b/src/index.d.ts`.
## Project C
```
// package.json
{
"main": "build/index.js",
"module": "build/index.modern.js",
"types": "build/index.d.ts",
"source": "src/index.ts",
"dependencies": {
"@my-workspace/project-b": "^1.0.0",
},
}
```
This project fails to build because it can't find the declaration file for `@my-workspace/project-b`.

## Issue
In my actual project I have 12 packages in a yarn workspace / lerna environment. The issue randomly happens for some projects and not others even though they all have the same microbundle and typescript config setup.

Start with the package.json declarations and the src/index.ts entry points in Projects A, B, and C, then inspect the microbundle and TypeScript configuration used across the Yarn workspace/Lerna packages. Reproduce the differing declaration output and trace why Project B writes build/project-b/src/index.d.ts. Done means every package emits its declaration at the configured build/index.d.ts path and downstream packages can resolve it.

Written by the indexing model from the issue text.