I tried out a theme in my D8 site that required a lot of contrib modules - which I installed with Composer (as many as were available, that is).
After deciding not to use the theme, I then uninstalled/removed those modules - also via Composer (for the "remove" step).
On many of them, I get this message:
Package "drupal/module_name" listed for update is not installed. Ignoring.
I see the module(s) listed in composer.json, and, of course, also in my /modules/conrib folder. Even though it says "Ignoring", it *usually* removes it from composer.lock and deletes the module folder from /modules/contrib.
In at least one case, though, it removed the module from composer.lock but didn't delete the module folder. And when I deleted the folder myself, during the next remove (on a completely different module), it re-installed the one I had removed previously.
Can anyone shed light on what's happening here?