What Kulkul shows works as long as you only have one instance of each group. You can test this in Revit (without Dynamo) and you will see that very often Revit gives a warning that “changing things in groups without editing the group is disallowed…but I’ll allow it since you only have one instance of that group…”. Go back and read the original post and look at the discussion between me and Dimitar…this was the exact conclusion and the solution as well.
The trick is to get all of the groups of the same type - duplicate that type as many times as needed so that you can have many single instance groups (so 20 instances of “Group 1” become “Group 1”, “Group 1_a”, “Group 1_b”, …). Then make the change to the elements as needed (it will be allowed since there are 20 unique group types). Then end that transaction and start another transaction in Dynamo and switch all of the duplicated groups back to “Group 1” and delete the now uneccesary duplicate groups and you should be in good shape. From the original post this is how you reset the group types:
