I think this is an Apple bug rather than a Scrivener one, because I’ve found it (and it’s CONfounded me!) in TextEdit also. Here goes:
I’ve got a bullet list with multiple entries. Somewhere down the list, I choose “none” to make a non-list paragraph. Boom, all my bullets disappear, and the lists are converted to plain paragraphs.
To terminate a list, simply tap Enter two times. Then the list is considered as finished, the last unused bullet (most of the times ) disappears as well.
Oh yes… Lists and tables are horrible - and horribly buggy too (you will even find they throw exceptions on the Console from time to time, which can make everything start acting odd - not good). Unfortunately, as you note, it’s an Apple bug, and there is not much I can do about it. (I can’t even make lists unavailable, given that they are built into the ruler!). I was really disappointed that lists and tables weren’t improved at all in Leopard. To make lists myself, I generally avoid the built-in feature and use Option-8 for bullets and a suitable paragraph style with a first line indent and tab etc.