WordPress plugins marked as Inactive for WordPress Multisite instance

Symptoms

• WordPress plugins are marked as Inactive for WordPress Multisite instance in Wordpress ToolKit.
• If choosing several plugins and attempting to activate them, Plesk reports that plugins are enabled. However, next attempt to open Plugins pop-up shows that they still have Inactive status.
• In WordPress Multisite admin panel on the network level, it can be observed that plugin is enabled and has Network Activated status
• The following entry in Plesk /usr/local/psa/admin/log/panel.log with debug mode enabled:

  CONFIG_TEXT: Warning: Plugin '<plugin_name>' is already network active.

Cause

Plesk WordPress Toolkit manages only plugins for the main site of WordPress Multisite.

Resolution

This can be ignored since the plugin is enabled on the network level.

Plesk does not officially support multisite WordPress installation so use it at your own risk.

Vote for the feature on User Voice for adding multisite instances support: https://plesk.uservoice.com/forums/184549-feature-suggestions/suggestions/31272292-wordpress-plugins-status-for-multisite-instances

Top-ranked ones are likely to be included in next versions of Plesk.