Group public instances opening without explination

So i seem to keep seeing a group public instance (that I moderate) having an instance open, and the thing is, I keep finding that even when I log off and no instances were open, an instance is open again when I log on later. I know for a fact only mods can create instances, and none of them were on at the time, as well as it not showing up in the logs for the group. Is there an explanation as to why these instances keep opening on their own?

I would really like a possible answer or solution, the instances still are randomly opening