Thank you for reporting this.
While trying to reproduce, I have identified two bugs and one of them probably hit you.
Can you please update the plugin to the latest version 59640f1 and see if that resolves the issue.
The plugin still does not deal with renaming groups very well. If you rename a group you should save the rules from all groups that depend on it (just enter a space after the boolean expression and remove it again to enable the Save button). This will be addressed in a later version.