the editor loads the same css as any other page but it is not in the same context depending on what kind of selectors are used to style the lists those selectors may not be in context in the editor.

For example in Artisteer skins there may be selectors like this to style lists:

.art-blockcontent-body ul li { }
.art-post ol, .art-post ul{}
.art-post li {}
.art-post li ol, .art-post li ul {}
.art-post ol>li { }

but those selectors are not in context in the editor because the editor is just article content html inside an iframe it doesn't have the containers around it with those classes like it will have when viewed in the page.

So it requires some additional CSS to style them the same in the editor, you can harvest the style rules from those selectors and then put the same rules in a new selectors like:

body.wysiwygeditor ul li { }

Hope that helps,

Joe