Environment - New Session?

I open Environment, make changes, and close. Save session.
Then when I re-open I see the bottom banner with my normal routes and session and now a pictorial entry.
I click on it to see what it offers but there is no EDIT offered. This new (environment) session does not allow editing??

Something doesn't sound right here, and I need to check that. Are you actually clicking on the new session and not on one of the advertisements for a DLC route? I ask because I've made the same mistake and that had me totally confused.

What I do when I make an environment change is wiggle a tree afterwards to force the program to save the route and offer me the opportunity to save just the route and not the session.

A bit eccentric but effective.

If you see a picture of a session in the banner at the bottom of the View Sessions screen and the picture has no Edit option when you select it, then it is a Saved Driver Game, not a full editable session.

John is correct with his suggestion "wiggle a tree" and then save after making an environment setting change. A change to an environment setting alone is not seen as a change to a route or a session - this has always been the case.

I suspect that the cause of this is because the environment settings are stored in both the route and the session (with only one exception - the World Origin which is stored in the route only). Since the route and the session can have different environment settings (e.g. Summer for the route and Winter for a session) then the program does not "know" whether to store a change in the route or the session. So "wiggling a tree" will mark the route as changed and save the new setting in the route. Making a change to something in the session (e.g. move a consist) will mark the session as changed and save the new setting in the session.

My theories anyway.