If you can't close a tactical meeting, the problem is usually that there are incomplete meeting outputs. It's possible that a project has not been assigned to a person or similar.
If you select the Triage Issues tab and then try to close the meeting from there, you should see the errors pop up. After you fix those, you should be able to close the meeting.
Here is an example of a meeting output that would cause an error, because of no one being selected in the "person" field:
And here is the error that would pop up if you try to close the meeting before fixing it: