classic editor activated again

Hello,
I recently updated a website to use the Gutenberg editor and created a series of events with Gutenberg blocks. When I opened one of these events in the backend yesterday the classic editor was active, although the rest of the website uses Gutenberg editor. All events are back to classic and I cannot access some of the Gutenberg blocks. The front end does show the Gutenberg blocks.

I guess this has something to do with the last update of the plugin which was installed two days ago. The classic editor plugin is deactivated on the website.

Will there be an update to enable Gutenberg again? Or is the whole plugin back to classic editor?

Thanks,
Wiebke