I had a similar problem and solved by adding this to my `nx.json`:
``` "pluginsConfig": { "@nrwl/js": { "analyzeSourceFiles": true } } ```
And this two options to my `build` target (I'm using `@nrwl/web:rollup`) in the `project.json`:
``` "updateBuildableProjectDepsInPackageJson": true, "buildableProjectDepsInPackageJsonType": "dependencies" ```

Finally found a solution, adding this to my `nx.json`:
``` "pluginsConfig": { "@nrwl/js": { "analyzeSourceFiles": true } } ```
And this two options to my `build` target (I'm using `@nrwl/web:rollup`) in the `project.json`:
``` "updateBuildableProjectDepsInPackageJson": true, "buildableProjectDepsInPackageJsonType": "dependencies" ```