I’ve recently converted an old theme from Classic Editor to Block Editor – however, I’m getting the WSOD as mentioned in other posts.
Inspecting the code, I can see the following:
<div id="metaboxes" class="hidden">
</div>
Remove class hidden, I can see the editor, but no way of saving.
First thing you should do is to enable displaying of errors so that hopefully you will get some information that might tell you why you are getting WSOD. https://codex.wordpress.org/WP_DEBUG