unfortunately, there are some things which look fine in the client, but cannot be rendered properly in AJAX - like rounded textboxes (there is a blog post on this around here). Apparently, that line_style is among those.
I am not aware of any workaround for this. With the textboxes, there is a slightly different setting which can be used so the round textboxes can be rendered in AJAX - there might be a way for the dotted line. I am not aware of any way, though. Sorry.