This is an issue I've experienced several times but it's just today I was able to see the whole "process". I've tried to look at this site for any related issues but I was unable, so if this is a duplicate I'll just raise my shield.
Sometimes, I notice an increment update of my points by 15 (like if someone had accepted my answer on some question). Normally, after 2-3 seconds, the
Recent achievements icon changes its shape and shows how much points have been added to my reputation with a green background, but when this issue happens, it just doesn't appear: I just see the points added.
So at this point, I have some new 15 points in my reputation and as I don't see where they come from, I try opening my profile and see my last reputation movements: absolutely nothing, and the 15 points that were added get dropped. So basically I have the same reputation before I noticed those points were added. If I don't update the page I still keep the new reputation (until I reload).
As there's no harm, it's curiosity what I feel: Why does this happen? Is it some kind of bug?