Discovery.zen.minimum_master_nodes: 7 but still getting split brain

Hi --

I have the following in my settings:

{
  "persistent": {
    "discovery": {
      "zen": {
        "minimum_master_nodes": "7"
      }
    }
  }
}

Yet twice in the past week, I've had clusters with nodes less than 7 split off from my 12 node cluster and start up their own cluster.

Do I need another setting to avoid split brain?

Thanks in advance,

That's pretty odd what version are you on, are you running cross datacentre?
It'd be easier if you just used something like 3 and then had dedicated masters, or just have 3 master eligible out of the 12.

Why are you passing the value as a string instead of an intager?

I actually pass it as an integer but when I pull it out of the settings it
comes back as a string.