I somehow excluded all my "admin.py" files from linter-flake8 2.0.2 for atom. So every file is perfectly monitored by the linter-flake8 except my admin.py files in different folders. I don't know how that happened. It's not in the .flake8 - configuration excludes
so it works again... reinstall linter or atom-linter plugin won't work. But reopen the project folder does fix the bug...