In reply to Josepha.

@Drew Jaynes
@Josepha
I was actually reporting the issue to Astra support and they reacted promptly and directed me to the Trac ticket that was already linked here. As turns out it was not theme/plugin related this time but really a Gutenberg/Core issue.

I have NO issue with beta versions having bugs, really not.

But in this case it is a bit different: the whole Meta Box topic is essential for the whole Gutenberg debate and migration to this editor, it's at the heart of it.

I would have expected a trunk nightly to have these kinds of bugs and crashes but really NOT the first beta version of 5.0.

May sound ignorant, I know, but the Gutenberg team was also kind of hard in listening to feedback from the community as a whole, especially the profound critics from users and developers alike.

But to be fair: just today I reached out to Gutenberg GitHub issues with a help request for one of my plugins: one guy from the community could help me and point me in the right direction. This is the WordPress community that I know and love. Thanks to you!

And so you don't get me wrong: I have yet to make my personal peace with Gutenberg, right, but I work all of my spare time to make my free .org plugins compatible where it is needed, because I feel responsible for my users! And the users themselves decide if they like Gutenberg and use it or not.

And, my last point, the Gutenberg/ Core/ Automattic team really challenges us users and developers a lot with the whole migration to Gutenberg / WordPress 5.0. I say it again: a lot! The engine of the airplane is changed during the flight.
Then it is more than natural, if there are also sometimes sharpenings, irony and satire. That may belong to it and you should endure that. We have to get along with Gutenberg.