I have noted the same problem as well, not successful to recreate, only let "GROUP > OPERATIONS > RESET RULES" and start again.
What you are seeing here is not an issue with v11.2, it's the way FEMAP's grouping has always worked. Your model has a group rule set up to include elements with certain ID numbers. When you perform any action on the group, the group rules get evaluated, and the resulting entities that match the rules are displayed.
If instead of removing nodes from the group, you just use the Group - Operations - Evaluate command, you will see the elements that are currently included in the group rules get displayed. You can turn on Group - Operations - Evaluate Always, and FEMAP will run the group rules at the beginning of every draw.
Understood, in fact, I have noted this happens after deleting mesh & remesh again, thanks!.