Steps to reproduce the issue

The user happens to be spam by coincidence
receive email:

Registration approval required for account of Gabe at ...

Hello administrator,

A new user has registered at xxxxx.
The user has verified their email address and requests that you approve their account.
This email contains their details:

Name : Gabe
email: doubtocomdi1986@hostcalls.com
Username: supepadmlnlspatop

You can activate the user by selecting on the link below:
http://www.xxxx/users-register?task=registration.activate&token=23bbecad5cde6f443349bb6a55b4c3e3

Expected result

When clicking on that link, I expect to be taken to user management but instead, clicking on that link auto activates user.

Actual result

So as this user was unwanted, I had to log in as superadmin and go to ...administrator/index.php?option=com_users&view=users. This user should be blocked but selecting the user and clicking on block has no effect except to produce the message that no user has been blocked.

note that the user Gabe was selected before clicking block but is automatically deselected during the clicking block action

note that clicking the green tick in the activate column whilst Gabe is selected, has no effect at all

System information (as much as possible)

Value

PHP Built On Linux uk14.siteground.eu 3.12.18-clouder0 #3 SMP Thu Oct 20 14:54:11 EEST 2016 x86_64
Database Version 5.6.28-76.1-log
Database Collation utf8_general_ci
Database Connection Collation utf8mb4_general_ci
PHP Version 5.6.29
Web Server Apache
WebServer to PHP Interface cgi-fcgi
Joomla! Version Joomla! 3.6.5 Stable [ Noether ] 1-December-2016 22:46 GMT updated 15 December 2016
Joomla! Platform Version Joomla Platform 13.1.0 Stable [ Curiosity ] 24-Apr-2013 00:00 GMT
User Agent Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/55.0.2883.87 Safari/537.36

Additional comments

These are the user options on this site: