Although the achievements label (the green reputation delta in the top bar) already has issues with open tabs, today things got a little weirder and worse.
First of all, the top bar in the open tab shows no new achievements anymore; new achievements remain ignored until you reload the page. Only after a reload or opening a new page do I see additional achievements listed.
The other problem is that the achievement box oversells me by a few hundred points from time to time. I saw this:
which would have been wonderful, except I already hit the rep cap on SO and gaining 310 points in a short time period without any answers on bountied questions is unlikely. And indeed, when opening the dropdown, I see:
I had gained an accept on a SO answer, nothing more. The +310 doesn't quite add up there, I gained 375 in total so far, across the network (the -5 on programmers is an unaccept plus an answer upvote). +310 is what I gained after 10:02 UTC, the point at which I had gained the first 65. I have certainly opened the dropdown in the intervening 2 hours and 36 minutes, which is also why the next line below the
+15 accept score is not highlighted.
The label was once more confused, after I received an accept followed by an un-accept as the OP tried to award the accepted answer mark to multiple answers:
Again, the update did not come in 'live' but only after I opened a new page, and again the score is 65 points off from the total for today, so far.