So long story short if I'm getting this right is: you're not seeing her drop from the campaign as much as you're used to and you're curious if there is a reason?

If so all I can say is it's probably a case of a "watched pot not boiling". 

When I was trying to get her to fuse relic keeper, I probably put 1200 energy in before I got one. Then when I was just trying to max out the campaign stars I'd get 2 or 3 in a row. That's the nature of random drops. 

Sorry if that's not much help, but at the least you can know they haven't lowered her drop rate, at least officially according to anything they put out.

She went from common.....skipped rare...and became non existent, as a resident conspircy theorist ...I feel like this was a tweak due to her sudden surge in popularity.

Warmaiden has been early game meta ever since, it's not a relatively recent thing. It's just like @AverageAmerican says- you feel like you get more if you're not exactly watching out for it. 

Maybe just bring along some food champs while you're looking for one. That way, you're more efficient with your energy. Good luck!

This isn't  a watch pot scenario here.... I imagine this happens to a lot of people.  I get it is the RNG . Im just wondering what triggers  it, was her loot table maybe adjusted even inadvertantly?

I just feel like its a strange coincidence, and you can go back and see all the tube guides and when they were created...there was a cocophany of praise for her all at the same time. I know shes been around awhile and nothing has changed in her to make he suddenly viable.  The Tube community has a tendency to be an echo chamber as well.....all basically putting out the same info at the same time...and eventually coming around to revisit it as well. 

She's was  dropping for me regular..had i known what I was doing at the time I would have been able to max 3 WM's  skills fully with the amount she was dropping for me...and it suddenly stopped. My own fool fault for not knowing any better..I mean i should  just use the books and be done with it already.

I stopped farming 9 altogether for her cause she just was not dropping...I've inefficiently wasted Tons of energy trying to farm her and yes i brought food with me.....as I mention I wasn't aware before, fully aware now.

You say you, "get it is the RNG" and then follow up with, "wondering what triggers it, was her loot table maybe adjusted even inadvertantly?".

I don't think you do get it.  You've had bad luck.  It happens.  I wonder how many Berserkers you pulled while trying for Warmaiden.  That's the more irritating part to me.

Well no..something  def changes ...RNG rules sure always in effect I know..but if the loot table is messed with that will effect the RNG outcome..

Either way I decided I just wasn't giving up I spend almost the entire month of feb on that  Map almost exclusively, only alternating between 3 and 6 , I don't think it should take a month to farm a farmable character like that. 

I also had the same issue with trying to farm Diabolist right after now that only took 2 weeks.

Another thing i noticed is I got more drops during the 2x events  I know the events are for shards but Most def saw more repeat drops of the same champs during those events.