Databases showing 0MB in cPanel 

From command line

1. Run the command.

# /usr/local/cpanel/bin/setupdbmap

2. Edit cPanel configuration file.

disk_usage_include_sqldbs=1 ( you need to set it to '1' if '0' ) in file /var/cpanel/cpanel.config

3. Run the following script.

#/scripts/update_db_cache

You can also enable this from the WHM control panel.

WHM >> Server Configuration >> Tweak Settings>>SQL>> Include databases in disk usage calculations