I'm having the exact same issue as the person in this topic:
Only in my case, it's with Tekken Tag Tournament 2.
Yesterday, I formatted my PS3 and I was pretty sure I synced my trophies with the server afterwards, but it turns out I didn't or something.
Half an hour ago, I finally decided to finish Tekken Tag Tournament 2 platinum because I was missing a trophy where I needed 2 controllers and today I finally got the second PS3 controller.
I got the last trophy for the platinum but no platinum??? I've never seen anything like this before. It said 99% completed and only platinum trophy was missing!
I synced the trophies few minutes after that situation and now the platinum appeared but it's delayed for 7 minutes... (the platinum never actually popped)
Is there a fix for it? Also, can mods confirm this is not flaggable?
I'm so mad right now, it makes me want to never touch PS3 ever again.
EDIT: I've contacted a person who had this issue here on the forums few years ago and he confirmed that it's a PS3 system error and thus not flaggable. Many other people had this issue as well and there have been topics about it already.