Lerna does no longer build browser-app module!?

Within my Node.js / yarn project I run into a strange problem. Suddenly my lerna build tool did no longer build my app module.

I am using a monorepo with module/directory structure like this

├── .gitignore
├── lerna.json
├── open-bpmn-app
├── open-bpmn-glsp
├── open-bpmn-theia
├── package.json
└── yarn.lock

The module ‘open-bpmn-app’ was ignored. As it turns out newer nx versions of lerna parse the .gitignore file in the root folder. You have to make sure that the root folder of your workspace packages is not excluded via .gitignore. In my case I had the following instructions included:

**/*-app/**
!**/*-app/package.json

By removing these two lines the problem was solved!

See also here and here.