So I spoke to Aran Linvail for the first time, and he tells me how he won't work with Hexxat without paying more. Rather than paying, I instead remove Hexxat from the party. Aran Linvail tells me I made the right decision and everything appears to continue smoothly with the next part needing me to help Mook and so on. I go and do some other stuff while waiting for night to fall before completing that part and return to Aran Linvail. Rather than continuing normally, he appears to be stuck in a permanent loop of the previous conversation, including the 'good decision' reassurance and Amulet of Power and Ring of Protection+2 rewards.