Yeah, I had the same thing happen to me in my servant route, but if anyone responded after I posted to ask if there was any fix for it, I managed to miss it.Also Vess seemed to kinda change her personality without being able to influence that, as there were no choices in between the episodes and at the end of episode 19 the romance path scene happened, although i was on the servant path.
If you find a fix or have one shown to you, I'd love to hear about it as well!
(Additionally, I did load up URM with path alerts, and the only path splits leading up to that were the ones specifically for her lines if you aren't on her servant path, and those triggered correctly for my being on her servant path, so she didn't have any lines leading up to the ruins, but then she still showed up in the options in camp there and had decidedly affectionate lines in that conversation)