I think you've asked this question elsewhere with similar results, Leo, but I may be mistaken who posted in that thread. If your rare was not hidden under a villager or a island feature (Like behind the statue) and you didn't pause to look for your collectible, then you probably have a glitch on your hands. I do know there are one or two people that swear up-and-down that the chief pointing doesn't work for them.

The collectible will always be rare. Villagers are a common source of frustration for a collectible-hunt, because their constant motion often has me overlooking sparkles that I would have seem on a still background. I often start a lecture, then drag the chief to the path before the villagers gather, to keep them out of the way. (Especially a problem with kids building sandcastles on top of my coral.)

I doubt that the collectible will remain for 10 minutes though; CFII has stated that it can take a couple of minutes to appear, but mine usually shows up pretty immediately after I get the sound effects and the "I used magic" rainbow over the chief's head. If you've been searching for 5 minutes, I wouldn't expect to find it at all.