I assumed that the whole purpose of a snapshot was to take a copy of the artifact at a point in time - including any environments, requirements test cases / plans / scripts associated with it at that time.

It would appear that in general on a plan, it does not retain the requirements or the environment settings.

On a Test case it does not retain the environments or requirements either ...

If I were to use a test plan for the purpose of regression testing, then I'd want the entire kit and kaboodle retained and have the ability to remove or add to that snapshot when I re-use it.

Is this perhaps an oversight that we've fixed ? or was it intended to be this way.