I had just that issue.
I had my first members and promoted ONE to Level 4 so he could invite others, but nothing else.

Then I came back and what happened ?
Everyone had level 9 and the one I gave 4 was leader.

He gave it back to me now, after 2-3 days.
I am very angry and the support didn't respond to me.
But @all players -> WATCH YOUR POSSE!

Don't let them steal your posse.

This shouldn't be possible, which means it's a bug. I'd PM Stephen about it, since that's a pretty big deal.

Im pretty sure he didn't steal you posse, I noticed there is a button u can click that says Promote to Posse Leader or something along those lines, I almost clicked it the other day and im pretty sure this is what u may have done. If so I hope there is some sort of confirmation text when clicking this button. If not then yeah its probably some sort of bug.

Glad to hear you got ur posse back thou

I know, I know that is very arrogant but it's just how it is: I am someone who doesn't click something accidently. I even read every EULA or other rules before I signup to something.

Also in game I check twice something like promotions and he was definitly only Level 4 and nothing else

As I said, in that point I am very! arrogant because I know what I do

At least the Support replied to me and said that they are still looking into it, what the cause has been (timeform right? I always miss "blafoo has been" and "blafoo was").

Also I have Screenshots of him agreeing to the whole cause in "stealing" the posse.

There was a bug, prior to posses going live, that auto-promoted a player to leader when the true leader logged out. That was fixed before go live, but it seems like there's still an issue.

For the record, when you click to promote someone to leader, there is a prompt.