PC, Chrome. I believe Blue's on an Android. For me it's happening when I like posts on the forum proper.
I'll try to make a note of it, although sometimes I don't actually notice for hours or days depending on how often I visit a given thread.
The most recent time it happened and I noticed was today, within a couple of minutes of Blue posting the thread about her storyboards in Alien Films, I had hit Like and it'd shown on my end as successful, but she informed me it wasn't showing and sure enough, when I went back to the page...
So it was a few minutes after whatever the time was when that thread was made.