Just tried this on the latest macOS 15 beta (4), still doesn't seem to be working.

I'm encountering this issue as well. Seems to be a regression, as it was working on macOS 13 before I upgraded my os. A couple other observations on Mac: When copying the list text from the NSTextView to the stock Notes app (and most other apps that support rich text), the list shows up correctly, including the markers. If I add nested bullets, it kind of triggers some of the markers to show up. When inspecting the underlying attributed string, the attributed string properties for the list items that display correctly are exactly the same as the properties for the list items that do not display correctly. The only difference is that the list item markers are not automatically prepended to the list item string on Mac (with the exception of the aforementioned nesting "hack").