In all likelihood there’s another plugin installed on your site that’s being quite aggressive in enqueuing its own CSS styles all over the WP admin. Best way to find it is disable each plugin (or theme), 1 at a time, and reload the Shield admin. When it loads normally, you’ve found the problem plugin. Feel free to share that with us when you find it and we can take a look… best thing though is to reach out to the problem plugin and ask them to be much more selective about which WP admin pages they’re enqueing their CSS styles, since they don’t need to force it on every admin page.
This problem applies to both free/paid Shield, but if you have any other issues pertaining to your pro licence and need support, please reach out to us using the link below as this is not the forum for premium plugin support.
https://support.onedollarplugin.com/form
Many thanks!
Paul.