Dear Jeff,
Good day! Thank you for posting to Microsoft Community. We are happy to assist you.
Based on your description you are still experiencing issues with the deleted shared channel.
Please conprehend that for Service Incidents that affected many tenants, when the Product team deploy the fixed, there is some possibility that some of the tenants' issues are not fixed, and it's difficult for the team to check the tenants one by one.
In this situation, we would suggest you contact the support team directly by going to Office 365 Admin Center-> Support-> New Service Request. The support engineers there have the correct escalation channel, and this is the most efficient way to report such issue. You can refer to this article to check the way how to raise a ticket: Ways to contact support for business products - Admin help. The engineers in related team have higher permission and resources than us to help check the root cause from background directly.
(Please use the admin account to open a case from support team, if you are not admin, kindly contact the IT admin in your tenant: For your reference: How do I find my Microsoft 365 admin? - Microsoft Support.)
If your tenant is still effected by the SI in the backend, the Support team would help run the fixes from the backend to resolve the issue for you.
I hope the information helps! If there is any update or I misunderstand you, please feel free to let me know. I will continue to assist you. Your understanding and co-operation are highly appreciated.
Thanks for your precious time. Have a nice day.
Sincerely,
Sherry | Microsoft Community Moderator