These dots working comes and goes, but recently including this morning they worked for me.
HunchBluntley: I don't know if anyone has a clue how their library update flags work these days. I get the feeling they might have to be tripped manually (not by design, but just because something broke in the badly engineered guts of the website, and they don't know how to fix it without breaking five other things, so they're stuck either doing this manually or...not doing it at all, which is where we were at for a couple months last year). If so, any backlogged dots probably won't show up until Monday, at the earliest.
EDIT: To more directly answer the question, I got a dot for
Grim Dawn (which did indeed get an update) in the last couple days, so the feature as a whole isn't completely broken.
It's actually not the website. The 'dots' are part of the Galaxy API infrastructure, the website only displays them. They do not get set manually, but when files are changed within the project and released for direct download (offline installers, zips and so on). And yep, that can be buggy as well.
And of course you also get a dot when a Mac or Linux version or foreign language files have been changed which do not concern you when you only want the english Windows version.