I dunno if this still happens in the 0.15.2 patch cause I'm trying not to trigger this bug anymore. But in the 0.14, I somehow found that if you activate the event to fight roushk (Which is if you'd be talking to Othra about choosing whether you should tell the others about the lake or not), you'll not be able to get the glowing amulet from her. Idk why that happens so ever since that happened I play the game by not doing much on Lizard tribe and just playing throughout the game until I discover the cave when I choose to look for another route in troll bridge. Idk if this still happens though...
Btw, I'm excited for the next update