I’m not doing anything fancy or non-simple. I’m using the most basic unnumbered bulleted list that Word offers – a simple dot.
The reason I showed the other variations of checkmark and square is to show some of the extent of the issue. I also checked how the other numbered list options available in Word translate into S3, and they all work as expected.
The unnumbered bullet list with the simple default dot as a bullet originating in Word is never successfully received by S3, whether via plain copy and paste or by file import. The first level of the list consistently displays its bullet (as in my screen cap above) not as a dot of some size, but as a what appears to be a numeric “fraction character” showing 35/17. thirty-five seventeenths, strange as it is.
To make sure, I just ran Word with nothing but 100% default settings… No special styles, no customizations.
Below is again what it looks like when brought into S3 (using a screencap cuz the 35/17 fraction character is stripped out when pasted into this post)
The first set is plain bullets, the second set is numbered. The first set has problems, the second doesn’t. .

I should mention that I am using Word 2007, though I doubt that matters, as these functions of Word probably haven’t been touched since well before then.
When I open the same document in Google Docs, the bullets display as expected.
When I create a list in a new Google Doc and bring that into S3, it displays as expected.
When I save the new Google Doc as a docx, open it in Word, and then bring that into S3, it displays as expected.
And when the original Word file is opened in google, saved as a google doc, then saved as a docx, and then brought into S3… by then whatever the issue is has been stripped out and it displays as expected.
It’s only plain unfancy unnumbered bulleted lists initially created in W that are not displaying correctly in S.
Whether or not this is an actual bug or doesn’t quite rise to that I’ll leave to others. .
Fortunately, it’s not difficult to deal with. And lists that originate in S have no issue when brought into W and back again.