I just check your staging website and confirm that it is one of your plugins causing the issue in your Global Blocks because when I disable all the plugins the global blocks are now working properly.
Please note that when I disable all the plugins the dashboard CSS and JS is not working properly.
I suggest that you disable all the plugins and activate them one by one to find the culprit in your live website. On the other hand, regarding the Content Modal not rendering. Please be advised that this is a known conflict between the latest release and WordPress 5.7. Our developers have already been informed about this issue and currently fixing it. A patch release will be rolling out anytime soon.
Please bear with us.