SlaveThreadCount at 0 for non-root user, should be 2

In MySQL 5.5 running on Ubuntu 14 in a master-master-slave configuration

From one of the masters, when executing the query below as a user with (ALL PRIVILEGES) on the database but no other privileges elsewhere, this query returns 0

SELECT COUNT(1) SlaveThreadCount 
FROM information_schema.processlist 
WHERE user='system user'

When executing the same user as root, I.E. (ALL PRIVILEGES) on everything, I get back the real slave count.

Any particular reason I'm getting back 0 and not the real SlaveThreadCount which is 2 in this case?

Is this is privileges issue?

If I run the query without there WHERE in the non-root user, I only see my processes.

SELECT * FROM information_schema.processlist

If I run it in a root user, then I see all processes.

So definitely a permissions issue, so looks like I need PROCESS, just answered my own question.