UPDATE:
Our developers have just implemented a fix for the issue you were seeing which is available in version 9.5.1. This version of the software is now available to download through our website.
If you originally downloaded Banktivity from IGG’s website directly, you can download the update through the following link on our website: https://www.banktivity.com/download.php
If you originally downloaded Banktivity from the App Store, you’ll need to update Banktivity through the App Store. We are currently waiting for Apple to approve the updated version of the app on their end, so we estimate that it will be available through the App Store later tonight.

We are investigating an issue with installing and using Banktivity 9.5 for users on Mac OS Big Sur and Catalina. Our developers are working on this issue.

9.5 is working properly under Mac OS Monterey and later.

In the meantime, you can revert to the previous stable version here: http://www.iggsoft.com/banktivity/Banktivity9.2.12-282.dmg

We apologize for any inconvenience this has caused.