On Responsive Container, Resize() is public and can be called at any time. If it is called when the object is not active in hierarchy, there seems to be some strange issues. I sometimes see NaN values, and things do not resize properly.
I have had some success by preventing Resize() as follows:
// Do not allow Resize if not active since object sizes may not be correct, unless in editor.
if (Application.isPlaying && !gameObject.activeInHierarchy)
But I still run into issues where the size is wrong when the object does become active.
I'm thinking for the public Resize() you need to check if active and if not, set a value so that when the object does become visible it will then call a private Resize().
I have also found that sometimes you need to wait an update or two before Resize() will get updated with correct sizes. This is especially noticeable on containers set to OnChange. So I'm thinking that maybe in these cases you let update run for 3 to 5 (or some config value) times that way it properly adjusts to other related objects as they also change.