This can correctly happen for a few reasons:
- The object isn't a "hidden object"; it's an object that another bear will give you.
- The hidden object is no longer on the island.
- Perhaps it got moved when the island regenerated itself, in which case you may get it back in the mail the following day.
- You picked it up and it's now in your backpack or Storage or a chest.
- A bug deleted the object. (The bug is obviously not correct behavior, but the fact that Ranger Bear won't give you a hint is correct.)
- The hidden object was ever picked up, even if you put the object back exactly where it was originally or the game automatically dropped it because your backpack was full.
There is a known bug where Ranger Bear will sometimes incorrectly think that there are no hidden objects. The bug is caused by a slightly incorrect save file, such that the game tries to give a hint for a hidden object that you've already found and fails since the object isn't hidden anymore, but the nature of the failure makes the game skip giving hints for unfound objects. The hint in the quest log may also be wrong in this case, still giving the hint for an already-found object.
- This bug is not yet fixed in version 5.1.0. I'm not sure it's completely fixed in 5.2.0, but at least one case is fixed so it should happen in fewer circumstances.
- If you are playing on iOS or a computer, you can send your save file to firstname.lastname@example.org and we can try to help you find the missing item.
- If you are playing on another platform, unfortunately your save can't be exported so you'll have to find the missing object yourself. I'd start looking near where the hint in the quest log says. But if you're unable to find it there then all bets are off. I'd make sure to search all piles (leaf piles, bone piles, piles with a broken urn, etc.) and dig up all dirt mounds since hidden objects are sometimes located in these rather than being out on the ground. Of course, you should also make sure to check on the ground, both in the open and behind other objects.