If you acknowledge a change in OpsCompass what must happen for that change to need to be acknowledged again?

Each change in your cloud that is a drift from a managed concern will trigger a new notification in OpsCompass.

So any changes that are acknowledged will be marked as "resolved" and any new changes (that haven't yet been acknowledged) will be marked as open. 

 

Additional Resources:
Who can acknowledge a change?

Can I see what changes have been acknowledged?