Cross-Section

Same issue. I started the quest, found the poison while exploring the town, talked to Tauwe, Ruanga (couldn't convince her to come, didn't mention the poison) and Kowha. Got the drinks, saw the poisoning of Kowha, end quest. Was a bit perplexed as to why I couldn't say anything about the poison at the Inn, so I looked up a guide and saw that you can mention it to Ruanga for a different ending. So I reloaded just before going to the Inn for the ending, went to Ruanga, talked about switching the poisons and convinced her to come with a Resolve check. But I didn't get any different dialogue when picking up the drinks nor when talking to the Captain, and poisoning proceeds as normal. Seems like it's fairly easy to break progression for the switcharoo ending.