Partial Configuration Import not working with extra language configurations

What are the steps required to reproduce the bug?

1. In settings set up a config directory: $config_directories['sync'] = 'sites/default/files/config/sync';
2. Enable all language related modules
3. Add a second language (german)
4. Go to Structure/Content Types / Article / Manage Fields / Body
5. Translate the body help text clicking on "Translate content fields"
6. Export all the configurations to the config directory (drush cex)
7. Now create a custom directory in web "myconfig" and copy "field.field.node.article.body.yml" file from config directory
8. Change the "description" config tag value to a random string
9. Run drush cim --source=myconfig --partial

What behavior were you expecting?
Only the original translation version of body configuration description (help text) will change to something else

What happened instead?

• Nothing changes in the body field active configruation
• All the german configuration will be removed from active configuration
• Lot of warnings and notices:

Miscellaneous

The problem is NOT drush related. The same happens if we do it via interface.
Configuration import / export has serious issues when multilingual configuration files are present!

Warning/notices:

Import the listed configuration changes? (y/n): y
array_keys() expects parameter 1 to be array, null given                    [warning]
StorageReplaceDataWrapper.php:131
array_keys() expects parameter 1 to be array, null given                    [warning]
StorageReplaceDataWrapper.php:131
array_keys() expects parameter 1 to be array, null given                    [warning]
StorageReplaceDataWrapper.php:131
array_keys() expects parameter 1 to be array, null given                    [warning]
StorageReplaceDataWrapper.php:131
array_keys() expects parameter 1 to be array, null given                    [warning]
StorageReplaceDataWrapper.php:131