OS: macOS Catalina 10.15
Margin Note: Version 2.7.18 (2.7.18002)
Welcome to the Forum.
Thanks for your report. Catalina really often meets Freeze when using MN. We’re still trying to locate the reason.
Although the issue may get better with Catalina update in the future. It is suggested to update the MN to latest 3.x version to get better compatible with new system Catalina since 2.x dev. has been stopped.
If you prefer the monopoly feature of 2.x like latex support etc. Maybe try to backup your files and reinstall the software helps.
Thank you for your support and suggestion, it doesn’t work after reinstall.