Please make sure that the export path you are writing out to is readable and writable by Topaz Video AI and that the path exists.
Try adding Video AI to the list of apps with ‘Full Disk Access’ in the macOS System Settings and restarting the app after: If this does not work, please proceed to a clean install which should reset the app’s permissions.
Uninstall Topaz Video AI by dragging and dropping the app into the trash bin