Hi there! I understand your Notion Calendar app is not responding on iOS and desktop, which used to work well before. Let's see if we can get it back up and running smoothly for you.

To start, could you tell me if this issue started happening after a recent update or change? Also, are you seeing any error messages or is the app simply not loading or syncing at all?

Meanwhile, here are some helpful steps you can try on your Mac (OS X 10.15.7) and iOS device:

1. Restart the app on both devices: Close Notion Calendar completely (force quit if needed) and reopen it to refresh the session.

2. Log out of your Notion account on both devices, then log back in. This can often fix syncing or authentication problems.

3. Make sure Notion and your device’s OS are fully updated to the latest versions available, as some bugs from prior releases are usually patched.

4. On your Mac desktop app, try this:
- Click "View" in the menu bar and select "Force reload" to refresh the app.
- If still unresponsive, select "Help" > "Troubleshooting" > "Reset & Erase All Local Data" to clear cache and reset the app (note this erases local data but your cloud data remains safe).

5. Check your internet connection is stable on both devices since syncing depends heavily on that.

6. If you connect your calendar via iCloud, ensure you have an app-specific password set up for Notion to access your iCloud calendar without issues. You can generate this password by logging into your Apple ID management page.

If you have tried some of these steps already, please let me know which ones worked or not so I can guide you further with alternatives or check if there are any ongoing server-side issues.

Are you comfortable trying these out? Let me know if you'd like me to walk you through any particular step!