Hi,
I have again the same problem. I try to put a field with MB view but there is no field. I have the same configuration at a different site and everything goes well. It's a setting page and custom field with a single image. I put all the details at the screens.
MB Views gets the field info and other data like posts, terms ... via WP REST API. So I think there is a problem with the REST API on your site. Please follow the Debugging Information step here to troubleshoot this issue https://support.metabox.io/topic/how-to-create-a-new-topic/
Can you please share the whole screen image after deactivating all plugins except Meta Box and MB Extensions? You can find the setting fields under the tab Site. Screenshot https://share.getcloudapp.com/2NulB8Pk
.
