Unfortunately the update contained code that was incompatible with macOS12, something that slipped through the beta process. We’ve just uploaded version 11.0.1, which should work again on 10.12. Could you give it a try and let us know if it indeed runs on 10.12? You can download it from https://downloads.agenda.com/Agenda_11.0.1.zip
Apologies for the hassle.
That’s odd, because the issue in this topic is about an issue on 10.12, which we since fixed in the 11.0.1 update. So very likely this is something else. When you say it won’t open. Do you see a crash report at all or it simply doesn’t want to launch at all without any warning or sign of issues? Does it help if you restart your MBP?