You must have had some kind of double transform going on in your original group. That is the only way you would get the objects within a DAG (Directed Acyclic Graph) group to appear to behave independently when you perform a transformation on the group.

I was going to make a video but I found this one and he does an excellent job of explaining double transforms and how to deal with them. I hope it helps.

https://lesterbanks.com/2011/09/deali...-when-rigging/

Generally freezing transforms and deleting history on the group will eliminate all inputs to the geometry except the parent group inputs and thus will fix the double transforms. But as the video above shows this will not be good if you want the inputs to stay associated with the geometry that is part of a DAG group. The two key things to take away from the video is 1. you can break the input from the parent DAG group on an object by unchecking the inherits transforms checkbox in the objects attribute node and 2. you can override the translate and rotate transforms of parent DAG group on an object by creating a parent constraint.