Multisite dashboard css not working after server transfer

After migrating servers, everything seemed to be working perfectly.

Initially the dashboards loaded correctly. Now I've disabled WP super cache and removed my domain from the previous server and the dashboard css isn't loading.

This is my .htaccess:
# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [L]
# uploaded files
RewriteRule ^files/(.+) wp-includes/ms-files.php?file=$1 [L]

# add a trailing slash to /wp-admin
RewriteRule ^wp-admin$ wp-admin/ [R=301,L]

RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^ - [L]
RewriteRule ^(wp-(content|admin|includes).*) $1 [L]
RewriteRule ^(.*\.php)$ $1 [L]
RewriteRule . index.php [L]
# END WordPress

File permissions are 755 for directories and 644 for files.

load-styles.php is shown at the beginning of the list of css files when I go to 'Inspect Element-Style Editor' in Firefox. That doesn't happen on dashboards with a working css.

My multisite is