Reward idols 'uncollect' themselves.

[Bieeanda]

I've noticed this in both Bolivia and Africa, but not Japan. Sometimes, for some reason that I've yet to identify, some of the idols lose their 'discovered' status. I've had to collect a couple of silvers in Bolivia twice, and earlier today while in Africa, I realized that after having found three silvers so far, only one was listed on my PDA tally.

Everything I'd collected in Africa was during one solid play-through, so it wasn't a matter of reloading a glitchy saved game.

[L Croft]

The only time it has happened to me is when I have reloaded a checkpoint which was saved before that point and then forgetting to pick the secret up again.

[noxdg]

Try this, after you collect a reward, go intot he menu and select "save rewards". If even if you die before a check point, the rewards should be retained.