Welcome to our forum, @Michael_Blackburn! Thanks for reaching out here as well as via email. As I mentioned there, we don’t yet offer collaborative annotations – papers on shared folders will show the annotations made by the sharer up to the point of sharing (visible to everyone), but those won’t stay updated – you would need to delete and re-add the file in order for new annotations to appear in the shared version of the file…
We realize this is not very seamless and are currently working on a whole new sharing structure, which will introduce collaborative annotations and many other features. Current expectation is for this to be released by the beginning of next year (or sooner).