Drush 9 pulling incorrect site information on Multi-site
I don’t know how your setup is now but you need to have something like this.

 sites/site-name-1/settings.php


Containing 

$databases['default']['default'] = array (
  'database' =&gt; 'gtest2018',
  'username' =&gt; 'gtest2018',
  'password' =&gt; '54352432346greg433',
  'prefix' =&gt; '',
  'host' =&gt; 'localhost',
  'port' =&gt; '3306',
  'namespace' =&gt; 'Drupal\\Core\\Database\\Driver\\mysql',
  'driver' =&gt; 'mysql',
);


And then the same for the other instances.

Then when you want to install a module in one instance run drush en MODULE_NAME -l site-name-1.

For more info look here: Multisite folder structure in Drupal 8.