Why is my microsoft teams channel ownerless?

I have heard from multiple sources that when a user is the only owner of a private channel on a team, but leaves the Office 365 group associated with that team, ownership of the private channel is automatically passed to another member of the team. However, I was curious and tested this, and the following happened:

1. User A adds a new channel to Team A and adds User B as a member.
2. User A leaves the Office 365 group connected to Team A through SharePoint.
3. User B is still a member of the channel; the channel is ownerless.

Why did Microsoft Teams not promote User B to owner of the channel?

This is an known issue. We are actively working on preventing it and doing the auto-promotion. For cases, when the private channels are already ownerless, it will require a tenant admin to list channel members first, and then promote someone in the channel:

https://learn.microsoft.com/en-us/powershell/module/teams/get-teamchanneluser?view=teams-ps https://learn.microsoft.com/en-us/powershell/module/teams/add-teamchanneluser?view=teams-ps