Yup, just confirming I had the same thing happen on the server - killed the troll, spoke to the captain who told me about the ancient one, spoke to the ancient one a few times (through the 'let me think about that' option) and he gave me the key and the charm, which completed the NPC quest, but the key didn't register in the HQM book (the charm did register in the book though).
The key does still work in the keyhole to transport you though, I landed virtually on top of a cool-looking stone brick pyramid ruin I hadn't seen before, it has waterfalls and lava traps inside and heaps of silverfish eggs in the walls! Guess I found my new (temporary) home