Hey @FreshView
We’ve recently updated the custom filter for premium plugin and theme detection.
There are now two filters, mainwp_detect_premium_plugins_update for improving detection of available updates, and mainwp_request_update_premium_plugins for improving the process of updating premium plugins.
More details in our KB: Premium Plugin Updates Not Detected - MainWP Documentation
You can quickly check the full slug by navigating to the WP Admin of a child site, and then hover the mouse over the Deactivate link for that plugin, and check the URL in the bottom left of your browser.
For example, for Akismet the slug is akismet/akismet.php
