Few weeks ago I created (I can't remember how) a list of words under "my lists", then I had to click on the "schedule" button, and it appeared under "mastery schedule" for learning and studying.
Today I couldn't remember how I did that and I clicked on "manage your schedules" then "add another schedule", and added my terms individually. This new list doesn't appear under "my lists".
So, what's the difference between the 2, and which one should I choose?
Lists that you make for My Lists (which you most likely made on Resources > Lesson Center) are just that, lists. They are a collection of words, kanji, grammar, etc, and can be studied in a non-scheduled manner (tap the study button, study all of them, repeat as much as you want)
Schedules are a collection of lists that renshuu will keep an eye on and schedule when you should study the contents in order to maximize your progress and minimize the time it takes to do that.
If you have any other information about that new list that you made (the name of it, or what you think the name is), I'd be happy to help you find it.