lol yeah it's really annoying. But I have noticed sometimes my upvotes don't register the first time, and I think it happens to others as well. I think either my phone or the site freezes for a second and it doesn't get recorded.
I have found if you look at something you've upvoted in imgflip.com/favorites the view and upvote count seems to be more accurate/up to date than what you see on the counts on the creation page.
What JB explained was happening to me too. I KNOW I left an upvote, and then when I come back, I'll see that it doesn't show my upvote and I have to click it again. OR in one case, it showed that I downvoted, and I certainly didn't mean to do that. It could also just be user error. :-)
I've noticed things can go wrong in terms of website functions if my phone switches between wifi and cellular data. I've seen duplicate comments with the same exact same image and text or somtimes comment images that didn't stick but show in my image pages.
I have to admit there are rare occasions where I see a creation I thought I upvoted but no green is there.
It was really annoying to open a notification just to see that someone upvoted, you know what I mean? 'Cause I'm gonna see how many upvotes I get anyway but, if I'm getting comments, I'd like to be able to start a reply thread, 'cause it's more fun that way.
Re-caption this meme
I have to admit there are rare occasions where I see a creation I thought I upvoted but no green is there.