PHPMyadmin does not show MySQL database in case if database name contains capital letters.
Internal software issue #PPPM-3405
The issue was fixed in Plesk 11.5 MU #31. Ensure that all microupdates are installed
The issue was fixed in Plesk 12.0 MU #69. Ensure that all microupdates are installed
The fix is considered to be included in future updates of Plesk.