Connect to Calendar opens Privacy window but doesn't register

What I did:
Click “Connect to Calendar” link from a note.

What happened:
Privacy tab of Security & Privacy System Preferences opened, but didn’t show entry for Agenda.

What I expected:
Privacy tab of Security & Privacy System Preferences would open, and show an entry for Agenda which I would then be able to check the box.

Things that might be helpful to know (Agenda version, OS and model, etc):
Agenda version: MAS 1.1
macOS: 10.13.2
MacBookPro (Retina, 15-inch, Mid 2014)

Any chance you previously denied Agenda access to your Calendar?

Does it help if you open the terminal.app and type:

tccutil reset Calendar

and then try it again?

Note that doing so might trigger other apps that you have given access to your Calendar (if any) to ask for access permission again.

Best wishes,
Alex