Composer update : Package "drupal/module_name" listed for update is not installed. Ignoring
I found what was the issue in my case. I post my solution. Even if it is specific to my issue, maybe it could help other users.

I didn’t install these  Drupal 8 modules. The developer who installed them used Drush (he should have used Composer). So I had the same modules installed twice, in /module and in modules/contrib I’ve deleted modules previously installed with drush  in /module and run composer update. That fixed the problem.