Hello! I understand that you're having trouble with Keyplan 3D not responding on your Mac running OS X 10.15.7. Let’s work together to get this sorted out.

First, can you provide more details about when this issue occurs? Is it happening when you open the application, while you're working on a project, or at a specific action within the app? Any additional information will help me assist you better.

In the meantime, let's try some basic troubleshooting steps. Here’s what you can do:

1. Force Quit the App:
- Click on the Apple logo in the top left corner of your screen.
- Select "Force Quit" from the dropdown menu.
- Locate Keyplan 3D in the list, select it, and click on "Force Quit."

2. Restart Your Mac:
- Sometimes, a simple restart can resolve issues. Click the Apple logo and select "Restart."

3. Update the App:
- Ensure that you have the latest version of Keyplan 3D. Open the App Store, go to the "Updates" tab, and see if there’s an update available for Keyplan 3D.

4. Check System Requirements:
- Confirm that your Mac meets the necessary system requirements for running Keyplan 3D efficiently.

If these steps don't resolve the issue, please let me know, and we can dive into some more advanced troubleshooting. I’m here to help!