This is the 2nd time in the last week that this has happened, so I'm reporting it here: When I logged onto my realm on tuesday, commandblockoutput gamerule was enabled (and consequently spamming chat due to one of our scoreboards). I disabled it promptly.

The realm was fine yesterday when multiple people were logging on and off.

When another admin logged onto the realm a few minutes ago, the commandblockoutput gamerule was enabled again! I've disabled it once more. I'll update this report if I have the issue again. This is not our players or admins enabling the gamerule. 

My theory is that admin log-ons re-enable commandblockoutput for some reason, but I need to test this more.