Native Plugins

Hi!

For my app in development I have a beta median app (free license) and a production app (professional license).
I'm currently working in the push notifications (via OneSignal). Some days ago OneSignal disappeared from my list of native plugins installed in my free app, I'm not sure why. This section only shows this text: "Free License: For access to native plugins contact Median support."

What can I do to re add it?