I logged out of LastPass and tried saving the API again and it is not working any better. I checked the site where the API is now correct (i fixed it last week) and it is still correct.
On one site that had fewer plugins, i deactivated all of them except for s2M, and it would not help at all. It still does not stick.
I made another test and put something as a Level3 list ID on a site where i don’t have any; when i saved, it DID save it correctly. So, i am wondering if the API key and the Level4 list ID are using variables that are shared with something else in WP. I thought it might have been the WP version as that one site was not running the latest one, but it still didn’t change anything.
Let me know if there is anything else i can try to help pinpoint. Right now, i am really stuck as members are not automatically added to my MC list for now.