Not showing any cache keys in Admin Panel > Spider Cache

[syaifulsz]

Hi, I've installed v6.0.0 from the master branch. I've moved the drop-ins files in wp-content and I enabled the plugin. It look like the cache is working, but it doesn't show any cache group or key in Admin Panel > Spider Cache.

I cleared all transient in database via WP-CLI wp transient delete --all, and browses the front-end and change few pages content in Admin Panel. No %_transient_% is found in wp_options table. It look like the cache is working and store caches on my memcached. But the Admin Panel > Spider Cache is empty.

My specification:

• Debian
• LEMP (PHP 7.0)
• Memcached
• WordPress 4.8.1