It could be related to that problem of Gribouillis + vote coming throug as 0 points in Python Forum I reported before. Good night, Dani. You need rest to debug your brain fresh! ;)
If you change style I would like the UI with one voting button (or hovering over the number) and then blue (text) positive vote and red (text) negative vote button. Or at least to have the box brought up by hovering to have blue or red frame and title/label 'positive vote' or 'negative vote'.
I do not think it is so big effect to only upvote the post as it only slowly raises the quality procent of poster and show in list if somebody clicks currently positive comments (which is not so much usefull as the posts are out of context).
Maybe the problem is also related to that I first hovered over negative side mistake, cancelled and refreshed. Now the vote is OK, maybe you fixed or it went by itself?
"Over the past few days..." Refreshing/revisiting is required during that timespan.
Since I am not on Daniweb 24/7 and I shut my computer down nightly, I revisit the site quite often over the span of a "few days". I'm sure somewhere in those few days a refresh happens -- like when the computer shuts down and the browser must restart the next day.
And today I have many "new" messages -- from 2-5 days ago.