You can never really see new posts as a guest, what worked was active topics but that is different from new posts. New posts cannot work as a guest because it needs to set a cookie for that. I have reactivated the "Active Post" link which is tied to search. So when I enable search for guests the Active Posts link will display because it is basically a search.
If you log out you will never see the Red "New Posts" link because that is tied to your user name.
I explain that here: https://dn.ca/topic/366/view-indicator-in-red/
At one point there were almost 200 guests using search and viewing the board and most of them were not registering as users because all the features are available to guests. So even though I turned the search and active links back on that may change if too many resources get used by guests. When I look at the stats I am seeing a lot of people from other boards visiting and using search and never registering. By removing search for guests it removes that active posts link and it is a toss up if we should leave it on or turned off. In the end we are encouraging participation and by giving all the features to guests we are not encouraging sign up.
So I activated it again until we discuss it further, maybe I can get some input for yes or no from members. I can go either way but my instinct tells me it should be shut off for guests to encourage sign ups.