Hi there! I understand that you can’t open the Glose app on your Mac to read your books. Let's see if we can get this sorted out together. Just to clarify, are you using the Glose app downloaded on your Mac, or are you accessing Glose through a browser? Also, do you get any error messages when you try to open the app?

Meanwhile, here are some general steps you can try on your macOS Catalina (10.15.7):

1. Restart the Mac: Sometimes a simple restart can fix app launch issues.
2. Update the Glose app: If you installed the app from the Mac App Store, check if there's an update available and install it.
3. Check for macOS updates: Make sure your system is fully updated by going to Apple menu > System Preferences > Software Update.
4. Force Quit and Relaunch: If the app seems to open but get stuck, try pressing Command + Option + Escape to open the Force Quit window, select Glose if it's listed, and click Force Quit. Then try reopening it.
5. Clear Cache or Preferences: Sometimes corrupt preferences cause launch issues. You can try deleting the Glose app's preference files located in ~/Library/Preferences/ (look for anything with "Glose" in the name). Don’t delete other files.
6. Reinstall the App: Uninstall Glose by dragging it to the Trash and then download and install the latest version from the Mac App Store or directly from Glose's website.

If these steps don't work or if you get any specific error messages, let me know so I can guide you further!

Are you satisfied with the steps I've provided so far?