In the Lien case we were first told that she had left of her own free will, then it was changed to that tale about writers not capable of writing for the character and that was all a "mutual agreement". I can also recall two events when members of two very famous rock bands had left the bands due to "mutual agreements" and it was many years later revealed from all parts that the both members were fired, one because the other members in the band simply wanted another person to join the band and the other because he objected to the musical direction the manager and another leading member of the band wanted.
I must admit that every time I see the word "mutual agreement" show up when someone leaves a successful project under mysterious circumstances, then I get suspicious and in most cases I've been right in my suspicions.
This applies to everything in life. If you get fired from a job, dumped by a partner, bomb out at school make sure you come up with the perfect line to give people explaining it and make sure you stick to it. If you have only one line people find it harder to read between.
...but it very well could be many reasons
If TPTB gave reason and Lien herself supports it, why still question it? Do Kes fans believe the actress they love is lying to them too? So everyone is lying....except the fans that were never on the set and don't know any of these folks personally, yet they're convinced NONE of them is telling the truth? So they're fans of someone they don't even trust at her word. Lien must be flattered to hear such things from her own fans, it explains why she doesn't do many Cons.
Whether they are or not, it's nearly a decade later. Nothing said or done can change it, so what's continuing to question it going to do? Voyager isn't going back into production and Lien isn't getting her job back. So even IF we find out what they said was a lie, what is it really going to change? If Kes fans REALLY are that upset, then they will still will be upset. Why carry around anger over something you still can't prove and can never change? What good is it ever going to do?