After update to WP 5.7 --custom field changes are not saved after editing a post

MB 5.3.9, AIO 1.13.4 and WP 5.7

Problem is caused with the Unsortable Metabox plugin https://wordpress.org/plugins/unsortable-meta-box/, not really Metabox.io's fault, but I think I got the recommendation for that plugin from you. The problem is a custom field metabox that I put in the sidebar for the client and put that with screenshots in the user documentation is accidentally moved by a user when they click the up or down arrow instead of the close triangle on the field. Since this plugin no longer works with Metabox, can you recommend an alternative to disable the "sorting" of my custom field metaboxes.

Here's the problem that the plugin causes with Metabox.io custom fields:

Any changes I make in radio, URL, text, etc. fields then update, the changed data shows in the field, but then I refresh the page while still in the backend and the fields revert back to the previous state. Or after I update the post and view the post the displayed custom fields have not been updated.