I saw Kate Mulgrew a couple years ago when she was in Melbourne and during the Q and A some idiot stood up and asked her in that rambling way people do at cons.. "so I've heard these rumors and I don't know if they are true or not, I really think they might just be rumors but I've read a lot of them and I don't know if they're true but I'm wondering is it true that you and Jeri Ryan had a huge conflict on the set and don't like each other?"
And boy was there a reaction. Mulgrew had been very lively and happy up to this point, seemed to be having a great time. At this question she lowered her microphone and her head and paced back and forth a couple times, then turned towards the guy that asked it and fixed him with the Janeway Death Glare. She said in the Janeway Death Glare Voice, "Oh I think you DO believe those rumors because I don't think you would have asked this question if you did not." Guy starts spluttering and she does that great Mulgrew hand held up thing where everything STOPS.
Then she told us that yes she resented that the first woman captain which she was very invested in being was going to be undermined by a sex symbol which is what all the publicity told them Jeri was going to be. Here she was, refusing a relationship for Janeway to not undermine her captaincy and now they were bringing on this person who was by all they had seen there to sex the whole thing up.
She then went on to say that the character became much more than that and that Jeri is a great professional actor etc.. but that initially it was taken very badly as a downgrade for the show.
I don't recall her mentioning Lien but I've read elsewhere she got on well with her, so I'd imagine that may have come into it too.
And that was it. I'd imagine she was probably a bitch but really this was years ago and she seems to want to get over it.